diff --git a/app/assets/javascripts/discourse/app/instance-initializers/url-redirects.js b/app/assets/javascripts/discourse/app/instance-initializers/url-redirects.js
index 71876e6fa65..a90b9eb6c94 100644
--- a/app/assets/javascripts/discourse/app/instance-initializers/url-redirects.js
+++ b/app/assets/javascripts/discourse/app/instance-initializers/url-redirects.js
@@ -1,21 +1,10 @@
 import DiscourseURL from "discourse/lib/url";
 import { initializeDefaultHomepage } from "discourse/lib/utilities";
-import escapeRegExp from "discourse-common/utils/escape-regexp";
 
 export default {
   after: "inject-objects",
 
   initialize(owner) {
-    const currentUser = owner.lookup("service:current-user");
-    if (currentUser) {
-      const username = currentUser.get("username");
-      const escapedUsername = escapeRegExp(username);
-      DiscourseURL.rewrite(
-        new RegExp(`^/u/${escapedUsername}/?$`, "i"),
-        `/u/${username}/activity`
-      );
-    }
-
     // We are still using these for now
     DiscourseURL.rewrite(/^\/group\//, "/groups/");
     DiscourseURL.rewrite(/^\/groups$/, "/g");
diff --git a/app/assets/javascripts/discourse/app/lib/url.js b/app/assets/javascripts/discourse/app/lib/url.js
index a2bc259757a..98de54535a8 100644
--- a/app/assets/javascripts/discourse/app/lib/url.js
+++ b/app/assets/javascripts/discourse/app/lib/url.js
@@ -247,8 +247,6 @@ const DiscourseURL = EmberObject.extend({
       path = withoutPrefix(path);
     }
 
-    path = rewritePath(path);
-
     if (typeof opts.afterRouteComplete === "function") {
       schedule("afterRender", opts.afterRouteComplete);
     }
diff --git a/app/assets/javascripts/discourse/app/mapping-router.js b/app/assets/javascripts/discourse/app/mapping-router.js
index 6c051f26af2..b16edde3d44 100644
--- a/app/assets/javascripts/discourse/app/mapping-router.js
+++ b/app/assets/javascripts/discourse/app/mapping-router.js
@@ -1,5 +1,4 @@
 import EmberRouter from "@ember/routing/router";
-import { rewritePath } from "discourse/lib/url";
 import { defaultHomepage } from "discourse/lib/utilities";
 import Site from "discourse/models/site";
 import { isTesting } from "discourse-common/config/environment";
@@ -9,7 +8,6 @@ const BareRouter = EmberRouter.extend({
   location: isTesting() ? "none" : "discourse-location",
 
   handleURL(url) {
-    url = rewritePath(url);
     const params = url.split("?");
 
     if (params[0] === "/" || params[0] === "") {
diff --git a/app/assets/javascripts/discourse/app/routes/unknown.js b/app/assets/javascripts/discourse/app/routes/unknown.js
index 084b9a683c9..53e564115bc 100644
--- a/app/assets/javascripts/discourse/app/routes/unknown.js
+++ b/app/assets/javascripts/discourse/app/routes/unknown.js
@@ -1,38 +1,47 @@
+import { inject as service } from "@ember/service";
 import { ajax } from "discourse/lib/ajax";
-import DiscourseURL from "discourse/lib/url";
+import DiscourseURL, { rewritePath } from "discourse/lib/url";
 import DiscourseRoute from "discourse/routes/discourse";
 
-export default DiscourseRoute.extend({
-  model(_, transition) {
+export default class UnknownRoute extends DiscourseRoute {
+  @service router;
+
+  async model(_, transition) {
     const path = transition.intent.url;
 
     if (!this.currentUser && this.siteSettings.login_required) {
       return;
     }
 
-    return ajax("/permalink-check.json", {
+    const rewrittenPath = rewritePath(path);
+    if (rewrittenPath !== path) {
+      this.router.transitionTo(rewrittenPath);
+      return;
+    }
+
+    const permalinkResults = await ajax("/permalink-check.json", {
       data: { path },
-    }).then((results) => {
-      if (results.found) {
-        // Avoid polluting the history stack for external links
-        transition.abort();
-
-        let url = results.target_url;
-
-        if (transition._discourse_anchor) {
-          // Remove the anchor from the permalink if present
-          url = url.split("#")[0];
-
-          // Add the anchor from the transition
-          url += `#${transition._discourse_anchor}`;
-        }
-
-        DiscourseURL.routeTo(url);
-        return "";
-      } else {
-        // 404 body HTML
-        return results.html;
-      }
     });
-  },
-});
+
+    if (permalinkResults.found) {
+      // Avoid polluting the history stack for external links
+      transition.abort();
+
+      let url = permalinkResults.target_url;
+
+      if (transition._discourse_anchor) {
+        // Remove the anchor from the permalink if present
+        url = url.split("#")[0];
+
+        // Add the anchor from the transition
+        url += `#${transition._discourse_anchor}`;
+      }
+
+      DiscourseURL.routeTo(url);
+      return "";
+    } else {
+      // 404 body HTML
+      return permalinkResults.html;
+    }
+  }
+}
diff --git a/app/assets/javascripts/discourse/app/routes/user-index.js b/app/assets/javascripts/discourse/app/routes/user-index.js
index 8801a93388b..e0ade535df2 100644
--- a/app/assets/javascripts/discourse/app/routes/user-index.js
+++ b/app/assets/javascripts/discourse/app/routes/user-index.js
@@ -34,7 +34,7 @@ export default class UserIndex extends DiscourseRoute {
 
     let destination;
     if (viewingMe) {
-      destination = "user.activity";
+      destination = "userActivity";
     } else {
       destination = this.viewingOtherUserDefaultRoute;
     }
diff --git a/app/assets/javascripts/discourse/tests/acceptance/group-index-test.js b/app/assets/javascripts/discourse/tests/acceptance/group-index-test.js
index 7570a21109f..389afa2c1a0 100644
--- a/app/assets/javascripts/discourse/tests/acceptance/group-index-test.js
+++ b/app/assets/javascripts/discourse/tests/acceptance/group-index-test.js
@@ -1,4 +1,4 @@
-import { click, visit } from "@ember/test-helpers";
+import { click, currentURL, visit } from "@ember/test-helpers";
 import { test } from "qunit";
 import {
   acceptance,
@@ -145,3 +145,31 @@ acceptance("Group Members", function (needs) {
     );
   });
 });
+
+async function visitWithRedirects(url) {
+  try {
+    await visit(url);
+  } catch (error) {
+    const { message } = error;
+    if (message !== "TransitionAborted") {
+      throw error;
+    }
+  }
+}
+
+acceptance("Old group route redirections", function () {
+  test("/group/discourse is redirected", async function (assert) {
+    await visitWithRedirects("/group/discourse");
+    assert.strictEqual(currentURL(), "/g/discourse");
+  });
+
+  test("/groups/discourse is redirected", async function (assert) {
+    await visitWithRedirects("/groups/discourse");
+    assert.strictEqual(currentURL(), "/g/discourse");
+  });
+
+  test("/groups is redirected", async function (assert) {
+    await visitWithRedirects("/groups");
+    assert.strictEqual(currentURL(), "/g");
+  });
+});