diff --git a/scripts/langindex.json b/scripts/langindex.json
index fd706d2f8..c61abf87b 100644
--- a/scripts/langindex.json
+++ b/scripts/langindex.json
@@ -654,6 +654,8 @@
   "addon.mod_forum.numreplies": "local_moodlemobileapp",
   "addon.mod_forum.pindiscussion": "forum",
   "addon.mod_forum.pinupdated": "forum",
+  "addon.mod_forum.postaddedsuccess": "forum",
+  "addon.mod_forum.postingroup": "local_moodlemobileapp",
   "addon.mod_forum.postisprivatereply": "forum",
   "addon.mod_forum.posttoforum": "forum",
   "addon.mod_forum.posttomygroups": "forum",
diff --git a/src/addons/mod/forum/classes/forum-discussions-source.ts b/src/addons/mod/forum/classes/forum-discussions-source.ts
index 7ef18281f..f525f4d02 100644
--- a/src/addons/mod/forum/classes/forum-discussions-source.ts
+++ b/src/addons/mod/forum/classes/forum-discussions-source.ts
@@ -15,8 +15,11 @@
 import { Params } from '@angular/router';
 import { CoreRoutedItemsManagerSource } from '@classes/items-management/routed-items-manager-source';
 import { CoreUser } from '@features/user/services/user';
+import { CoreGroupInfo, CoreGroups } from '@services/groups';
+import { CoreUtils } from '@services/utils/utils';
 import {
     AddonModForum,
+    AddonModForumCanAddDiscussion,
     AddonModForumData,
     AddonModForumDiscussion,
     AddonModForumProvider,
@@ -35,7 +38,12 @@ export class AddonModForumDiscussionsSource extends CoreRoutedItemsManagerSource
     forum?: AddonModForumData;
     trackPosts = false;
     usesGroups = false;
+    supportsChangeGroup = false;
     selectedSortOrder: AddonModForumSortOrder | null = null;
+    groupId = 0;
+    groupInfo?: CoreGroupInfo;
+    allPartsPermissions?: AddonModForumCanAddDiscussion;
+    canAddDiscussionToGroup = true;
 
     constructor(courseId: number, cmId: number, discussionsPathPrefix: string) {
         super();
@@ -94,12 +102,20 @@ export class AddonModForumDiscussionsSource extends CoreRoutedItemsManagerSource
      * @inheritdoc
      */
     getItemQueryParams(discussion: AddonModForumDiscussionItem): Params {
-        return {
+        const params: Params = {
             courseId: this.COURSE_ID,
             cmId: this.CM_ID,
             forumId: this.forum?.id,
-            ...(this.isOnlineDiscussion(discussion) ? { discussion, trackPosts: this.trackPosts } : {}),
         };
+
+        if (this.isOnlineDiscussion(discussion)) {
+            params.discussion = discussion;
+            params.trackPosts = this.trackPosts;
+        } else if (this.isNewDiscussionForm(discussion)) {
+            params.groupId = this.usesGroups ? this.groupId : undefined;
+        }
+
+        return params;
     }
 
     /**
@@ -133,6 +149,42 @@ export class AddonModForumDiscussionsSource extends CoreRoutedItemsManagerSource
         }
     }
 
+    /**
+     * Load group info.
+     */
+    async loadGroupInfo(forumId: number): Promise<void> {
+        [this.groupInfo, this.allPartsPermissions] = await Promise.all([
+            CoreGroups.getActivityGroupInfo(this.CM_ID, false),
+            CoreUtils.ignoreErrors(AddonModForum.canAddDiscussionToAll(forumId, { cmId: this.CM_ID })),
+        ]);
+
+        this.supportsChangeGroup = AddonModForum.isGetDiscussionPostsAvailable();
+        this.usesGroups = !!(this.groupInfo.separateGroups || this.groupInfo.visibleGroups);
+        this.groupId = CoreGroups.validateGroupId(this.groupId, this.groupInfo);
+
+        await this.loadSelectedGroupData();
+    }
+
+    /**
+     * Load some specific data for current group.
+     *
+     * @return Promise resolved when done.
+     */
+    async loadSelectedGroupData(): Promise<void> {
+        if (!this.usesGroups) {
+            this.canAddDiscussionToGroup = true;
+        } else if (this.groupId === 0) {
+            this.canAddDiscussionToGroup = !this.allPartsPermissions || this.allPartsPermissions.status;
+        } else if (this.forum) {
+            const addDiscussionData = await AddonModForum.canAddDiscussion(this.forum.id, this.groupId, { cmId: this.CM_ID });
+
+            this.canAddDiscussionToGroup = addDiscussionData.status;
+        } else {
+            // Shouldn't happen, assume the user can.
+            this.canAddDiscussionToGroup = true;
+        }
+    }
+
     /**
      * @inheritdoc
      */
@@ -174,6 +226,7 @@ export class AddonModForumDiscussionsSource extends CoreRoutedItemsManagerSource
             cmId: this.forum.cmid,
             sortOrder: this.selectedSortOrder.value,
             page,
+            groupId: this.groupId,
         });
         let discussions = response.discussions;
 
@@ -252,6 +305,36 @@ export class AddonModForumDiscussionsSource extends CoreRoutedItemsManagerSource
         return offlineDiscussions;
     }
 
+    /**
+     * Invalidate cache data.
+     *
+     * @return Promise resolved when done.
+     */
+    async invalidateCache(): Promise<void> {
+        const promises: Promise<void>[] = [];
+
+        promises.push(AddonModForum.invalidateForumData(this.COURSE_ID));
+
+        if (this.forum) {
+            promises.push(AddonModForum.invalidateDiscussionsList(this.forum.id));
+            promises.push(AddonModForum.invalidateCanAddDiscussion(this.forum.id));
+            promises.push(CoreGroups.invalidateActivityGroupInfo(this.forum.cmid));
+        }
+
+        await Promise.all(promises);
+    }
+
+    /**
+     * Invalidate list cache data.
+     *
+     * @return Promise resolved when done.
+     */
+    async invalidateList(): Promise<void> {
+        if (this.forum) {
+            await AddonModForum.invalidateDiscussionsList(this.forum.id);
+        }
+    }
+
 }
 
 /**
diff --git a/src/addons/mod/forum/components/index/index.html b/src/addons/mod/forum/components/index/index.html
index 5ddd4c954..cf24dd7d5 100644
--- a/src/addons/mod/forum/components/index/index.html
+++ b/src/addons/mod/forum/components/index/index.html
@@ -23,6 +23,20 @@
             </ion-item>
         </core-course-module-info>
 
+        <ion-item class="ion-text-wrap core-group-selector" lines="none"
+            *ngIf="supportsChangeGroup && groupInfo && (groupInfo.separateGroups || groupInfo.visibleGroups)">
+            <ion-label id="addon-forum-groupslabel">
+                <ng-container *ngIf="groupInfo.separateGroups">{{'core.groupsseparate' | translate }}</ng-container>
+                <ng-container *ngIf="groupInfo.visibleGroups">{{'core.groupsvisible' | translate }}</ng-container>
+            </ion-label>
+            <ion-select [(ngModel)]="groupId" (ionChange)="groupChanged()" aria-labelledby="addon-forum-groupslabel"
+                interface="action-sheet" [interfaceOptions]="{header: 'core.group' | translate}">
+                <ion-select-option *ngFor="let groupOpt of groupInfo.groups" [value]="groupOpt.id">
+                    {{groupOpt.name}}
+                </ion-select-option>
+            </ion-select>
+        </ion-item>
+
         <!-- Cut-off date or due date message -->
         <ion-card class="core-info-card" *ngIf="availabilityMessage">
             <ion-item>
@@ -39,6 +53,17 @@
             </ion-item>
         </ion-card>
 
+        <!-- Cannot add discussion to group messages. -->
+        <ion-card class="core-info-card" *ngIf="usesGroups && canAddDiscussion && !canAddDiscussionToGroup">
+            <ion-item>
+                <ion-icon name="fas-info-circle" slot="start" aria-hidden="true"></ion-icon>
+                <ion-label>
+                    <span *ngIf="groupId <= 0">{{ 'addon.mod_forum.cannotadddiscussionall' | translate }}</span>
+                    <span *ngIf="groupId > 0">{{ 'addon.mod_forum.cannotadddiscussion' | translate }}</span>
+                </ion-label>
+            </ion-item>
+        </ion-card>
+
         <ng-container *ngIf="forum">
             <core-empty-box *ngIf="!discussions || !discussions.hasDiscussions" icon="far-comments"
                 [message]="'addon.mod_forum.forumnodiscussionsyet' | translate">
@@ -128,7 +153,7 @@
     <core-course-module-navigation collapsible-footer [hidden]="showLoading" [courseId]="courseId" [currentModuleId]="module.id">
     </core-course-module-navigation>
 
-    <ion-fab slot="fixed" core-fab vertical="bottom" horizontal="end" *ngIf="forum && canAddDiscussion">
+    <ion-fab slot="fixed" core-fab vertical="bottom" horizontal="end" *ngIf="canAddDiscussionToGroup">
         <ion-fab-button (click)="openNewDiscussion()" [attr.aria-label]="addDiscussionText">
             <ion-icon name="fas-plus" aria-hidden="true"></ion-icon>
             <span class="sr-only">{{ addDiscussionText }}</span>
diff --git a/src/addons/mod/forum/components/index/index.scss b/src/addons/mod/forum/components/index/index.scss
index 4fb44d094..cb8ebcfdb 100644
--- a/src/addons/mod/forum/components/index/index.scss
+++ b/src/addons/mod/forum/components/index/index.scss
@@ -52,4 +52,8 @@
 
     }
 
+    .core-group-selector {
+        border-top: 1px solid var(--spacer-color);
+    }
+
 }
diff --git a/src/addons/mod/forum/components/index/index.ts b/src/addons/mod/forum/components/index/index.ts
index 33c844ddf..59aa22c5e 100644
--- a/src/addons/mod/forum/components/index/index.ts
+++ b/src/addons/mod/forum/components/index/index.ts
@@ -31,7 +31,7 @@ import { AddonModForumOffline } from '@addons/mod/forum/services/forum-offline';
 import { Translate } from '@singletons';
 import { CoreCourseContentsPage } from '@features/course/pages/contents/contents';
 import { AddonModForumHelper } from '@addons/mod/forum/services/forum-helper';
-import { CoreGroups, CoreGroupsProvider } from '@services/groups';
+import { CoreGroupInfo } from '@services/groups';
 import { CoreEvents, CoreEventObserver } from '@singletons/events';
 import {
     AddonModForumAutoSyncData,
@@ -42,7 +42,6 @@ import {
 import { CoreSites } from '@services/sites';
 import { CoreUser } from '@features/user/services/user';
 import { CoreDomUtils } from '@services/utils/dom';
-import { CoreUtils } from '@services/utils/utils';
 import { CoreCourse } from '@features/course/services/course';
 import { CoreSplitViewComponent } from '@components/split-view/split-view';
 import { AddonModForumDiscussionOptionsMenuComponent } from '../discussion-options-menu/discussion-options-menu';
@@ -82,9 +81,9 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
     availabilityMessage: string | null = null;
     sortingAvailable!: boolean;
     sortOrders: AddonModForumSortOrder[] = [];
-    canPin = false;
     hasOfflineRatings = false;
     showQAMessage = false;
+    isSetPinAvailable = false;
     sortOrderSelectorModalOptions: ModalOptions = {
         component: AddonModForumSortOrderSelectorComponent,
     };
@@ -123,6 +122,36 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
         return this.discussions?.getSource().selectedSortOrder ?? undefined;
     }
 
+    get supportsChangeGroup(): boolean {
+        return this.discussions?.getSource().supportsChangeGroup ?? false;
+    }
+
+    get groupId(): number {
+        return this.discussions?.getSource().groupId ?? 0;
+    }
+
+    set groupId(value: number) {
+        if (this.discussions) {
+            this.discussions.getSource().groupId = value;
+        }
+    }
+
+    get groupInfo(): CoreGroupInfo | undefined {
+        return this.discussions?.getSource().groupInfo;
+    }
+
+    get usesGroups(): boolean {
+        return !!(this.discussions?.getSource().usesGroups);
+    }
+
+    get canPin(): boolean {
+        return !!(this.isSetPinAvailable && this.discussions?.getSource().allPartsPermissions?.canpindiscussions);
+    }
+
+    get canAddDiscussionToGroup(): boolean {
+        return !!(this.forum && this.canAddDiscussion && this.discussions?.getSource().canAddDiscussionToGroup);
+    }
+
     /**
      * Check whether a discussion is online.
      *
@@ -150,6 +179,7 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
         this.addDiscussionText = Translate.instant('addon.mod_forum.addanewdiscussion');
         this.sortingAvailable = AddonModForum.isDiscussionListSortingAvailable();
         this.sortOrders = AddonModForum.getAvailableSortOrders();
+        this.isSetPinAvailable = AddonModForum.isSetPinStateAvailableForSite();
 
         this.sortOrderSelectorModalOptions.componentProps = {
             sortOrders: this.sortOrders,
@@ -383,19 +413,10 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
         const promises: Promise<void>[] = [];
 
         // Check if the activity uses groups.
-        promises.push(
-            CoreGroups.instance
-                .getActivityGroupMode(forum.cmid)
-                .then(async mode => {
-                    discussions.getSource().usesGroups =
-                        mode === CoreGroupsProvider.SEPARATEGROUPS || mode === CoreGroupsProvider.VISIBLEGROUPS;
-
-                    return;
-                }),
-        );
+        promises.push(discussions.getSource().loadGroupInfo(forum.id));
 
         promises.push(
-            AddonModForum.instance
+            AddonModForum
                 .getAccessInformation(forum.id, { cmId: this.module.id })
                 .then(async accessInfo => {
                     // Disallow adding discussions if cut-off date is reached and the user has not the
@@ -410,26 +431,6 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
                 }),
         );
 
-        if (AddonModForum.isSetPinStateAvailableForSite()) {
-            // Use the canAddDiscussion WS to check if the user can pin discussions.
-            promises.push(
-                AddonModForum.instance
-                    .canAddDiscussionToAll(forum.id, { cmId: this.module.id })
-                    .then(async response => {
-                        this.canPin = !!response.canpindiscussions;
-
-                        return;
-                    })
-                    .catch(async () => {
-                        this.canPin = false;
-
-                        return;
-                    }),
-            );
-        } else {
-            this.canPin = false;
-        }
-
         await Promise.all(promises);
     }
 
@@ -461,21 +462,8 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
      * @return Promise resolved when done.
      */
     protected async fetchSortOrderPreference(): Promise<void> {
-        const getSortOrder = async () => {
-            if (!this.sortingAvailable) {
-                return null;
-            }
-
-            const value = await CoreUtils.ignoreErrors(
-                CoreUser.getUserPreference(AddonModForumProvider.PREFERENCE_SORTORDER),
-            );
-
-            return value ? parseInt(value, 10) : null;
-        };
-
         const discussions = await this.promisedDiscussions;
-        const value = await getSortOrder();
-        const selectedOrder = this.sortOrders.find(sortOrder => sortOrder.value === value) || this.sortOrders[0];
+        const selectedOrder = await AddonModForum.getSelectedSortOrder();
 
         discussions.getSource().selectedSortOrder = selectedOrder;
 
@@ -492,11 +480,11 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
     protected async invalidateContent(): Promise<void> {
         const promises: Promise<void>[] = [];
 
-        promises.push(AddonModForum.invalidateForumData(this.courseId));
+        if (this.discussions) {
+            promises.push(this.discussions.getSource().invalidateCache());
+        }
 
         if (this.forum) {
-            promises.push(AddonModForum.invalidateDiscussionsList(this.forum.id));
-            promises.push(CoreGroups.invalidateActivityGroupMode(this.forum.cmid));
             promises.push(AddonModForum.invalidateAccessInformation(this.forum.id));
         }
 
@@ -545,36 +533,52 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
      * @param isNewDiscussion Whether it's a new discussion event.
      * @param data Event data.
      */
-    protected eventReceived(
+    protected async eventReceived(
         isNewDiscussion: boolean,
         data: AddonModForumNewDiscussionData | AddonModForumReplyDiscussionData,
-    ): void {
-        if ((this.forum && this.forum.id === data.forumId) || data.cmId === this.module.id) {
-            this.showLoadingAndRefresh(false).finally(() => {
-                // If it's a new discussion in tablet mode, try to open it.
-                if (isNewDiscussion && CoreScreen.isTablet) {
-                    const newDiscussionData = data as AddonModForumNewDiscussionData;
-                    const discussion = this.discussions?.items.find(disc => {
-                        if (this.discussions?.getSource().isOfflineDiscussion(disc)) {
-                            return disc.timecreated === newDiscussionData.discTimecreated;
-                        }
-
-                        if (this.discussions?.getSource().isOnlineDiscussion(disc)) {
-                            return (newDiscussionData.discussionIds ?? []).includes(disc.discussion);
-                        }
-
-                        return false;
-                    });
-
-                    if (this.discussions && (discussion || !this.discussions.empty)) {
-                        this.discussions.select(discussion ?? this.discussions.items[0]);
-                    }
-                }
-            });
-
-            // Check completion since it could be configured to complete once the user adds a new discussion or replies.
-            this.checkCompletion();
+    ): Promise<void> {
+        if ((!this.forum || this.forum.id !== data.forumId) && data.cmId !== this.module.id) {
+            return; // Not current forum.
         }
+
+        // Check completion since it could be configured to complete once the user adds a new discussion or replies.
+        this.checkCompletion();
+
+        try {
+            if (isNewDiscussion) {
+                CoreDomUtils.showToast('addon.mod_forum.postaddedsuccess', true);
+
+                const newDiscGroupId = (data as AddonModForumNewDiscussionData).groupId;
+
+                if (!newDiscGroupId || newDiscGroupId < 0 || !this.groupId || newDiscGroupId === this.groupId) {
+                    await this.showLoadingAndRefresh(false);
+                } else {
+                    // Discussion is in a different group than the one currently viewed, only invalidate data.
+                    await this.discussions?.getSource().invalidateList();
+                }
+            } else {
+                await this.showLoadingAndRefresh(false);
+            }
+        } finally {
+            // If it's a new discussion in tablet mode, try to open it.
+            if (isNewDiscussion && CoreScreen.isTablet && this.discussions) {
+                const newDiscussionData = data as AddonModForumNewDiscussionData;
+                const discussion = this.discussions.items.find(disc => {
+                    if (this.discussions?.getSource().isOfflineDiscussion(disc)) {
+                        return disc.timecreated === newDiscussionData.discTimecreated;
+                    }
+
+                    if (this.discussions?.getSource().isOnlineDiscussion(disc)) {
+                        return (newDiscussionData.discussionIds ?? []).includes(disc.discussion);
+                    }
+
+                    return false;
+                });
+
+                this.discussions.select(discussion ?? null);
+            }
+        }
+
     }
 
     /**
@@ -661,6 +665,24 @@ export class AddonModForumIndexComponent extends CoreCourseModuleMainActivityCom
         }
     }
 
+    /**
+     * Group has changed.
+     */
+    async groupChanged(): Promise<void> {
+        const modal = await CoreDomUtils.showModalLoading();
+
+        try {
+            await Promise.all([
+                this.discussions?.getSource().loadSelectedGroupData(),
+                this.discussions?.reload(),
+            ]);
+        } catch (error) {
+            CoreDomUtils.showErrorModalDefault(error, 'core.errorloadingcontent', true);
+        } finally {
+            modal.dismiss();
+        }
+    }
+
 }
 
 /**
@@ -696,7 +718,7 @@ class AddonModForumDiscussionsManager extends CoreListItemsManager<AddonModForum
         }
 
         try {
-            await AddonModForum.instance.logView(forum.id, forum.name);
+            await AddonModForum.logView(forum.id, forum.name);
 
             CoreCourse.checkModuleCompletion(this.page.courseId, this.page.module.completiondata);
         } catch {
diff --git a/src/addons/mod/forum/lang.json b/src/addons/mod/forum/lang.json
index 1c30bcf6a..fc6d78c16 100644
--- a/src/addons/mod/forum/lang.json
+++ b/src/addons/mod/forum/lang.json
@@ -45,6 +45,8 @@
     "numreplies": "{{numreplies}} replies",
     "pindiscussion": "Pin this discussion",
     "pinupdated": "The pin option has been updated.",
+    "postaddedsuccess": "Your post was successfully added.",
+    "postingroup": "Posting in group \"{{groupname}}\".",
     "postisprivatereply": "This is a private reply. It is only visible to you and anyone with the capability to view private replies, such as teachers or managers.",
     "posttoforum": "Post to forum",
     "posttomygroups": "Post a copy to all groups",
diff --git a/src/addons/mod/forum/pages/new-discussion/new-discussion.html b/src/addons/mod/forum/pages/new-discussion/new-discussion.html
index efe7b9dc0..f403daa71 100644
--- a/src/addons/mod/forum/pages/new-discussion/new-discussion.html
+++ b/src/addons/mod/forum/pages/new-discussion/new-discussion.html
@@ -49,7 +49,7 @@
                     <ion-label id="addon-mod-forum-groupslabel">{{ 'addon.mod_forum.group' | translate }}</ion-label>
                     <ion-select [(ngModel)]="newDiscussion.groupId" [disabled]="newDiscussion.postToAllGroups"
                         aria-labelledby="addon-mod-forum-groupslabel" interface="action-sheet" name="groupid"
-                        [interfaceOptions]="{header: 'addon.mod_forum.group' | translate}">
+                        [interfaceOptions]="{header: 'addon.mod_forum.group' | translate}" (ionChange)="calculateGroupName()">
                         <ion-select-option *ngFor="let group of groups" [value]="group.id">{{ group.name }}</ion-select-option>
                     </ion-select>
                 </ion-item>
@@ -66,7 +66,11 @@
                     [allowOffline]="true" [courseId]="courseId">
                 </core-attachments>
             </div>
-            <ion-item>
+            <ion-item *ngIf="showGroups && groupName && !newDiscussion.postToAllGroups" class="addon-forum-group-info">
+                <ion-icon name="fas-info-circle" slot="start" aria-hidden="true"></ion-icon>
+                <ion-label>{{ 'addon.mod_forum.postingroup' | translate:{groupname: groupName} }}</ion-label>
+            </ion-item>
+            <ion-item class="addon-forum-new-discussion-buttons">
                 <ion-label>
                     <ion-row>
                         <ion-col *ngIf="hasOffline">
diff --git a/src/addons/mod/forum/pages/new-discussion/new-discussion.page.ts b/src/addons/mod/forum/pages/new-discussion/new-discussion.page.ts
index bd1592ce4..a4bb114e9 100644
--- a/src/addons/mod/forum/pages/new-discussion/new-discussion.page.ts
+++ b/src/addons/mod/forum/pages/new-discussion/new-discussion.page.ts
@@ -61,6 +61,7 @@ type NewDiscussionData = {
 @Component({
     selector: 'page-addon-mod-forum-new-discussion',
     templateUrl: 'new-discussion.html',
+    styleUrls: ['new-discussion.scss'],
 })
 export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLeave {
 
@@ -91,6 +92,7 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
     advanced = false; // Display all form fields.
     accessInfo: AddonModForumAccessInformation = {};
     courseId!: number;
+    groupName?: string;
 
     discussions?: AddonModForumNewDiscussionDiscussionsSwipeManager;
 
@@ -102,6 +104,7 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
     protected isDestroyed = false;
     protected originalData?: Partial<NewDiscussionData>;
     protected forceLeave = false;
+    protected initialGroupId?: number;
 
     constructor(protected route: ActivatedRoute, @Optional() protected splitView: CoreSplitViewComponent) {}
 
@@ -115,6 +118,10 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
             this.cmId = CoreNavigator.getRequiredRouteNumberParam('cmId');
             this.forumId = CoreNavigator.getRequiredRouteNumberParam('forumId');
             this.timeCreated = CoreNavigator.getRequiredRouteNumberParam('timeCreated');
+            this.initialGroupId = CoreNavigator.getRouteNumberParam('groupId');
+
+            // Discussion list uses 0 for all participants, but this page WebServices use a different value. Convert it.
+            this.initialGroupId = this.initialGroupId === 0 ? AddonModForumProvider.ALL_PARTICIPANTS : this.initialGroupId;
 
             if (this.timeCreated !== 0 && (routeData.swipeEnabled ?? true)) {
                 const source = CoreRoutedItemsManagerSourcesTracker.getOrCreateSource(
@@ -188,8 +195,9 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
                                     this.groups = forumGroups;
                                     this.groupIds = forumGroups.map((group) => group.id).filter((id) => id > 0);
                                     // Do not override group id.
-                                    this.newDiscussion.groupId = this.newDiscussion.groupId || forumGroups[0].id;
+                                    this.newDiscussion.groupId = this.newDiscussion.groupId || this.getInitialGroupId();
                                     this.showGroups = true;
+                                    this.calculateGroupName();
                                     if (this.groupIds.length <= 1) {
                                         this.newDiscussion.postToAllGroups = false;
                                     }
@@ -263,6 +271,7 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
                             this.newDiscussion.subscribe = !!discussion.options.discussionsubscribe;
                             this.newDiscussion.pin = !!discussion.options.discussionpinned;
                             this.messageControl.setValue(discussion.message);
+                            this.calculateGroupName();
 
                             // Treat offline attachments if any.
                             if (typeof discussion.options.attachmentsid === 'object' && discussion.options.attachmentsid.offline) {
@@ -377,6 +386,16 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
         return forumGroups.filter(forumGroup => userGroupsIds.indexOf(forumGroup.id) > -1);
     }
 
+    /**
+     * Get the initial group ID.
+     *
+     * @return Initial group ID.
+     */
+    protected getInitialGroupId(): number {
+        return (this.initialGroupId && this.groups.find(group => group.id === this.initialGroupId)) ?
+            this.initialGroupId : this.groups[0].id;
+    }
+
     /**
      * Add the "All participants" option to a list of groups if the user can add a discussion to all participants.
      *
@@ -453,6 +472,7 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
                 cmId: this.cmId,
                 discussionIds: discussionIds,
                 discTimecreated: discTimecreated,
+                groupId: this.showGroups && !this.newDiscussion.postToAllGroups ? this.newDiscussion.groupId : undefined,
             },
             CoreSites.getCurrentSiteId(),
         );
@@ -588,6 +608,17 @@ export class AddonModForumNewDiscussionPage implements OnInit, OnDestroy, CanLea
         this.advanced = !this.advanced;
     }
 
+    /**
+     * Calculate current group's name.
+     */
+    calculateGroupName(): void {
+        if (this.newDiscussion.groupId <= 0) {
+            this.groupName = undefined;
+        } else {
+            this.groupName = this.groups.find(group => group.id === this.newDiscussion.groupId)?.name;
+        }
+    }
+
     /**
      * Check if we can leave the page or not.
      *
diff --git a/src/addons/mod/forum/pages/new-discussion/new-discussion.scss b/src/addons/mod/forum/pages/new-discussion/new-discussion.scss
new file mode 100644
index 000000000..9ddfaed1c
--- /dev/null
+++ b/src/addons/mod/forum/pages/new-discussion/new-discussion.scss
@@ -0,0 +1,22 @@
+@import "~theme/globals";
+
+:host {
+    .addon-forum-group-info {
+        > ion-icon[slot] {
+            color: var(--ion-color-info);
+            @include margin-horizontal(null, 16px);
+        }
+    }
+
+    .addon-forum-new-discussion-buttons {
+        ion-label {
+            margin-top: 0;
+        }
+
+        ion-col {
+            padding-top: 0;
+            padding-bottom: 0;
+        }
+    }
+
+}
diff --git a/src/addons/mod/forum/services/forum.ts b/src/addons/mod/forum/services/forum.ts
index dc8d60079..9c2e1c989 100644
--- a/src/addons/mod/forum/services/forum.ts
+++ b/src/addons/mod/forum/services/forum.ts
@@ -159,19 +159,33 @@ export class AddonModForumProvider {
         return ROOT_CACHE_KEY + 'discussion:' + discussionId;
     }
 
+    /**
+     * Get common cache key for forum discussions list WS calls.
+     *
+     * @param forumId Forum ID.
+     * @return Cache key.
+     */
+    protected getDiscussionsListCommonCacheKey(forumId: number): string {
+        return ROOT_CACHE_KEY + 'discussions:' + forumId;
+    }
+
     /**
      * Get cache key for forum discussions list WS calls.
      *
      * @param forumId Forum ID.
      * @param sortOrder Sort order.
+     * @param groupId Group ID.
      * @return Cache key.
      */
-    protected getDiscussionsListCacheKey(forumId: number, sortOrder: number): string {
-        let key = ROOT_CACHE_KEY + 'discussions:' + forumId;
+    protected getDiscussionsListCacheKey(forumId: number, sortOrder: number, groupId?: number): string {
+        let key = this.getDiscussionsListCommonCacheKey(forumId);
 
         if (sortOrder != AddonModForumProvider.SORTORDER_LASTPOST_DESC) {
             key += ':' + sortOrder;
         }
+        if (groupId) {
+            key += `:group${groupId}`;
+        }
 
         return key;
     }
@@ -700,6 +714,26 @@ export class AddonModForumProvider {
         return sortOrders;
     }
 
+    /**
+     * Get sort order selected by the user.
+     *
+     * @return Promise resolved with sort order.
+     */
+    async getSelectedSortOrder(): Promise<AddonModForumSortOrder> {
+        const sortOrders = this.getAvailableSortOrders();
+        let sortOrderValue: number | null = null;
+
+        if (this.isDiscussionListSortingAvailable()) {
+            const preferenceValue = await CoreUtils.ignoreErrors(
+                CoreUser.getUserPreference(AddonModForumProvider.PREFERENCE_SORTORDER),
+            );
+
+            sortOrderValue = preferenceValue ? parseInt(preferenceValue, 10) : null;
+        }
+
+        return sortOrders.find(sortOrder => sortOrder.value === sortOrderValue) || sortOrders[0];
+    }
+
     /**
      * Get forum discussions.
      *
@@ -729,6 +763,7 @@ export class AddonModForumProvider {
             // Since Moodle 3.7.
             method = 'mod_forum_get_forum_discussions';
             (params as AddonModForumGetForumDiscussionsWSParams).sortorder = options.sortOrder;
+            (params as AddonModForumGetForumDiscussionsWSParams).groupid = options.groupId;
         } else {
             if (options.sortOrder !== AddonModForumProvider.SORTORDER_LASTPOST_DESC) {
                 throw new Error('Sorting not supported with the old WS method.');
@@ -945,10 +980,7 @@ export class AddonModForumProvider {
     async invalidateDiscussionsList(forumId: number, siteId?: string): Promise<void> {
         const site = await CoreSites.getSite(siteId);
 
-        await CoreUtils.allPromises(
-            this.getAvailableSortOrders()
-                .map(sortOrder => site.invalidateWsCacheForKey(this.getDiscussionsListCacheKey(forumId, sortOrder.value))),
-        );
+        await site.invalidateWsCacheForKeyStartingWith(this.getDiscussionsListCommonCacheKey(forumId));
     }
 
     /**
@@ -1499,6 +1531,7 @@ export type AddonModForumLegacyPost = {
 export type AddonModForumGetDiscussionsOptions = CoreCourseCommonModWSOptions & {
     sortOrder?: number; // Sort order.
     page?: number; // Page. Defaults to 0.
+    groupId?: number; // Group ID.
 };
 
 /**
@@ -2079,6 +2112,7 @@ export type AddonModForumNewDiscussionData = {
     cmId: number;
     discussionIds?: number[] | null;
     discTimecreated?: number;
+    groupId?: number; // The discussion group if it's created in a certain group, ALL_PARTICIPANTS for all participants.
 };
 
 /**
diff --git a/src/addons/mod/forum/services/handlers/prefetch.ts b/src/addons/mod/forum/services/handlers/prefetch.ts
index a460bc6e7..ed48fb29b 100644
--- a/src/addons/mod/forum/services/handlers/prefetch.ts
+++ b/src/addons/mod/forum/services/handlers/prefetch.ts
@@ -95,51 +95,80 @@ export class AddonModForumPrefetchHandlerService extends CoreCourseActivityPrefe
      * @param options Other options.
      * @return Promise resolved with array of posts.
      */
-    protected getPostsForPrefetch(
+    protected async getPostsForPrefetch(
         forum: AddonModForumData,
         options: CoreCourseCommonModWSOptions = {},
     ): Promise<AddonModForumPost[]> {
-        const promises = AddonModForum.getAvailableSortOrders().map((sortOrder) => {
+        // Only prefetch selected sort order.
+        const sortOrder = await AddonModForum.getSelectedSortOrder();
+
+        const groupsIds = await this.getGroupsIdsToPrefetch(forum);
+
+        const results = await Promise.all(groupsIds.map(async (groupId) => {
             // Get discussions in first 2 pages.
             const discussionsOptions = {
                 sortOrder: sortOrder.value,
+                groupId: groupId,
                 numPages: 2,
                 ...options, // Include all options.
             };
 
-            return AddonModForum.getDiscussionsInPages(forum.id, discussionsOptions).then((response) => {
-                if (response.error) {
-                    throw new Error('Failed getting discussions');
-                }
+            const response = await AddonModForum.getDiscussionsInPages(forum.id, discussionsOptions);
 
-                const promises: Promise<{ posts: AddonModForumPost[] }>[] = [];
+            if (response.error) {
+                throw new Error('Failed getting discussions');
+            }
 
-                response.discussions.forEach((discussion) => {
-                    promises.push(AddonModForum.getDiscussionPosts(discussion.discussion, options));
+            return await Promise.all(
+                response.discussions.map((discussion) => AddonModForum.getDiscussionPosts(discussion.discussion, options)),
+            );
+        }));
+
+        const posts: AddonModForumPost[] = [];
+        const postIds: Record<number, boolean> = {}; // To make the array unique.
+
+        results.forEach((groupResults) => {
+            groupResults.forEach((groupDiscussion) => {
+                groupDiscussion.posts.forEach((post) => {
+                    if (!postIds[post.id]) {
+                        postIds[post.id] = true;
+                        posts.push(post);
+                    }
                 });
-
-                return Promise.all(promises);
             });
         });
 
-        return Promise.all(promises).then((results) => {
-            // Each order has returned its own list of posts. Merge all the lists, preventing duplicates.
-            const posts: AddonModForumPost[] = [];
-            const postIds = {}; // To make the array unique.
+        return posts;
+    }
 
-            results.forEach((orderResults) => {
-                orderResults.forEach((orderResult) => {
-                    orderResult.posts.forEach((post) => {
-                        if (!postIds[post.id]) {
-                            postIds[post.id] = true;
-                            posts.push(post);
-                        }
-                    });
-                });
-            });
+    /**
+     * Get the group IDs to prefetch in a forum.
+     * Prefetch all participants if the user can view them. Otherwise, prefetch the groups the user can view.
+     *
+     * @param forum Forum instance.
+     * @return Promise resolved with array of group IDs.
+     */
+    protected async getGroupsIdsToPrefetch(forum: AddonModForumData): Promise<number[]> {
+        const groupInfo = await CoreGroups.getActivityGroupInfo(forum.cmid);
 
-            return posts;
-        });
+        const supportsChangeGroup = AddonModForum.isGetDiscussionPostsAvailable();
+        const usesGroups = !!(groupInfo.separateGroups || groupInfo.visibleGroups);
+
+        if (!usesGroups) {
+            return [0];
+        }
+
+        const allPartsGroup = groupInfo.groups?.find(group => group.id === 0);
+        if (allPartsGroup) {
+            return [0]; // Prefetch all participants.
+        }
+
+        if (!supportsChangeGroup) {
+            // Cannot change group, prefetch only the default group.
+            return [groupInfo.defaultGroupId];
+        }
+
+        return groupInfo.groups?.map(group => group.id) ?? [0];
     }
 
     /**
@@ -225,11 +254,6 @@ export class AddonModForumPrefetchHandlerService extends CoreCourseActivityPrefe
         // Prefetch access information.
         promises.push(AddonModForum.getAccessInformation(forum.id, modOptions));
 
-        // Prefetch sort order preference.
-        if (AddonModForum.isDiscussionListSortingAvailable()) {
-            promises.push(CoreUser.getUserPreference(AddonModForumProvider.PREFERENCE_SORTORDER, siteId));
-        }
-
         // Get course data, needed to determine upload max size if it's configured to be course limit.
         promises.push(CoreUtils.ignoreErrors(CoreCourses.getCourseByField('id', courseId, siteId)));
 
@@ -269,34 +293,15 @@ export class AddonModForumPrefetchHandlerService extends CoreCourseActivityPrefe
 
             // Activity uses groups, prefetch allowed groups.
             const result = await CoreGroups.getActivityAllowedGroups(forum.cmid, undefined, siteId);
-            if (mode === CoreGroupsProvider.SEPARATEGROUPS) {
-                // Groups are already filtered by WS. Prefetch canAddDiscussionToAll to determine if user can pin/attach.
-                await CoreUtils.ignoreErrors(AddonModForum.canAddDiscussionToAll(forum.id, options));
-
-                return;
-            }
-
-            if (canCreateDiscussions) {
-                // Prefetch data to check the visible groups when creating discussions.
-                const response = await CoreUtils.ignoreErrors(
-                    AddonModForum.canAddDiscussionToAll(forum.id, options),
-                    { status: false },
-                );
-
-                if (response.status) {
-                    // User can post to all groups, nothing else to prefetch.
-                    return;
-                }
-
-                // The user can't post to all groups, let's check which groups he can post to.
-                await Promise.all(
-                    result.groups.map(
-                        async (group) => CoreUtils.ignoreErrors(
-                            AddonModForum.canAddDiscussion(forum.id, group.id, options),
-                        ),
+            await Promise.all(
+                result.groups.map(
+                    async (group) => CoreUtils.ignoreErrors(
+                        AddonModForum.canAddDiscussion(forum.id, group.id, options),
                     ),
-                );
-            }
+                ).concat(
+                    CoreUtils.ignoreErrors(AddonModForum.canAddDiscussionToAll(forum.id, options)),
+                ),
+            );
         } catch (error) {
             // Ignore errors if cannot create discussions.
             if (canCreateDiscussions) {