diff --git a/src/BasePlatform.ts b/src/BasePlatform.ts
index c5f58f7f0c..520c3fbe46 100644
--- a/src/BasePlatform.ts
+++ b/src/BasePlatform.ts
@@ -25,6 +25,9 @@ import {CheckUpdatesPayload} from "./dispatcher/payloads/CheckUpdatesPayload";
 import {Action} from "./dispatcher/actions";
 import {hideToast as hideUpdateToast} from "./toasts/UpdateToast";
 
+export const HOMESERVER_URL_KEY = "mx_hs_url";
+export const ID_SERVER_URL_KEY = "mx_is_url";
+
 export enum UpdateCheckStatus {
     Checking = "CHECKING",
     Error = "ERROR",
@@ -47,6 +50,7 @@ export default abstract class BasePlatform {
 
     constructor() {
         dis.register(this.onAction);
+        this.startUpdateCheck = this.startUpdateCheck.bind(this);
     }
 
     protected onAction = (payload: ActionPayload) => {
@@ -217,11 +221,9 @@ export default abstract class BasePlatform {
 
     setLanguage(preferredLangs: string[]) {}
 
-    getSSOCallbackUrl(hsUrl: string, isUrl: string, fragmentAfterLogin: string): URL {
+    getSSOCallbackUrl(fragmentAfterLogin: string): URL {
         const url = new URL(window.location.href);
         url.hash = fragmentAfterLogin || "";
-        url.searchParams.set("homeserver", hsUrl);
-        url.searchParams.set("identityServer", isUrl);
         return url;
     }
 
@@ -232,8 +234,12 @@ export default abstract class BasePlatform {
      * @param {string} fragmentAfterLogin the hash to pass to the app during sso callback.
      */
     startSingleSignOn(mxClient: MatrixClient, loginType: "sso" | "cas", fragmentAfterLogin: string) {
-        const callbackUrl = this.getSSOCallbackUrl(mxClient.getHomeserverUrl(), mxClient.getIdentityServerUrl(),
-            fragmentAfterLogin);
+        // persist hs url and is url for when the user is returned to the app with the login token
+        localStorage.setItem(HOMESERVER_URL_KEY, mxClient.getHomeserverUrl());
+        if (mxClient.getIdentityServerUrl()) {
+            localStorage.setItem(ID_SERVER_URL_KEY, mxClient.getIdentityServerUrl());
+        }
+        const callbackUrl = this.getSSOCallbackUrl(fragmentAfterLogin);
         window.location.href = mxClient.getSsoLoginUrl(callbackUrl.toString(), loginType); // redirect to SSO
     }
 
diff --git a/src/Lifecycle.js b/src/Lifecycle.js
index 0494628472..d018ea99aa 100644
--- a/src/Lifecycle.js
+++ b/src/Lifecycle.js
@@ -41,6 +41,7 @@ import {IntegrationManagers} from "./integrations/IntegrationManagers";
 import {Mjolnir} from "./mjolnir/Mjolnir";
 import DeviceListener from "./DeviceListener";
 import {Jitsi} from "./widgets/Jitsi";
+import {HOMESERVER_URL_KEY, ID_SERVER_URL_KEY} from "./BasePlatform";
 
 /**
  * Called at startup, to attempt to build a logged-in Matrix session. It tries
@@ -163,14 +164,16 @@ export function attemptTokenLogin(queryParams, defaultDeviceDisplayName) {
         return Promise.resolve(false);
     }
 
-    if (!queryParams.homeserver) {
+    const homeserver = localStorage.getItem(HOMESERVER_URL_KEY);
+    const identityServer = localStorage.getItem(ID_SERVER_URL_KEY);
+    if (!homeserver) {
         console.warn("Cannot log in with token: can't determine HS URL to use");
         return Promise.resolve(false);
     }
 
     return sendLoginRequest(
-        queryParams.homeserver,
-        queryParams.identityServer,
+        homeserver,
+        identityServer,
         "m.login.token", {
             token: queryParams.loginToken,
             initial_device_display_name: defaultDeviceDisplayName,
@@ -256,8 +259,8 @@ function _registerAsGuest(hsUrl, isUrl, defaultDeviceDisplayName) {
  * @returns {Object} Information about the session - see implementation for variables.
  */
 export function getLocalStorageSessionVars() {
-    const hsUrl = localStorage.getItem("mx_hs_url");
-    const isUrl = localStorage.getItem("mx_is_url");
+    const hsUrl = localStorage.getItem(HOMESERVER_URL_KEY);
+    const isUrl = localStorage.getItem(ID_SERVER_URL_KEY);
     const accessToken = localStorage.getItem("mx_access_token");
     const userId = localStorage.getItem("mx_user_id");
     const deviceId = localStorage.getItem("mx_device_id");
@@ -486,9 +489,9 @@ function _showStorageEvictedDialog() {
 class AbortLoginAndRebuildStorage extends Error { }
 
 function _persistCredentialsToLocalStorage(credentials) {
-    localStorage.setItem("mx_hs_url", credentials.homeserverUrl);
+    localStorage.setItem(HOMESERVER_URL_KEY, credentials.homeserverUrl);
     if (credentials.identityServerUrl) {
-        localStorage.setItem("mx_is_url", credentials.identityServerUrl);
+        localStorage.setItem(ID_SERVER_URL_KEY, credentials.identityServerUrl);
     }
     localStorage.setItem("mx_user_id", credentials.userId);
     localStorage.setItem("mx_access_token", credentials.accessToken);
diff --git a/src/components/structures/MatrixChat.tsx b/src/components/structures/MatrixChat.tsx
index 058a7ba50b..9527d65eea 100644
--- a/src/components/structures/MatrixChat.tsx
+++ b/src/components/structures/MatrixChat.tsx
@@ -1942,7 +1942,10 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         // console.log(`Rendering MatrixChat with view ${this.state.view}`);
 
         let fragmentAfterLogin = "";
-        if (this.props.initialScreenAfterLogin) {
+        if (this.props.initialScreenAfterLogin &&
+            // XXX: workaround for https://github.com/vector-im/riot-web/issues/11643 causing a login-loop
+            !["welcome", "login", "register"].includes(this.props.initialScreenAfterLogin.screen)
+        ) {
             fragmentAfterLogin = `/${this.props.initialScreenAfterLogin.screen}`;
         }
 
diff --git a/src/components/structures/auth/SoftLogout.js b/src/components/structures/auth/SoftLogout.js
index 5d9f868f85..a2824b63a3 100644
--- a/src/components/structures/auth/SoftLogout.js
+++ b/src/components/structures/auth/SoftLogout.js
@@ -25,6 +25,7 @@ import {MatrixClientPeg} from "../../../MatrixClientPeg";
 import {sendLoginRequest} from "../../../Login";
 import AuthPage from "../../views/auth/AuthPage";
 import SSOButton from "../../views/elements/SSOButton";
+import {HOMESERVER_URL_KEY, ID_SERVER_URL_KEY} from "../../../BasePlatform";
 
 const LOGIN_VIEW = {
     LOADING: 1,
@@ -43,7 +44,7 @@ const FLOWS_TO_VIEWS = {
 export default class SoftLogout extends React.Component {
     static propTypes = {
         // Query parameters from MatrixChat
-        realQueryParams: PropTypes.object, // {homeserver, identityServer, loginToken}
+        realQueryParams: PropTypes.object, // {loginToken}
 
         // Called when the SSO login completes
         onTokenLoginCompleted: PropTypes.func,
@@ -90,7 +91,7 @@ export default class SoftLogout extends React.Component {
 
     async _initLogin() {
         const queryParams = this.props.realQueryParams;
-        const hasAllParams = queryParams && queryParams['homeserver'] && queryParams['loginToken'];
+        const hasAllParams = queryParams && queryParams['loginToken'];
         if (hasAllParams) {
             this.setState({loginView: LOGIN_VIEW.LOADING});
             this.trySsoLogin();
@@ -157,8 +158,8 @@ export default class SoftLogout extends React.Component {
     async trySsoLogin() {
         this.setState({busy: true});
 
-        const hsUrl = this.props.realQueryParams['homeserver'];
-        const isUrl = this.props.realQueryParams['identityServer'] || MatrixClientPeg.get().getIdentityServerUrl();
+        const hsUrl = localStorage.getItem(HOMESERVER_URL_KEY);
+        const isUrl = localStorage.getItem(ID_SERVER_URL_KEY) || MatrixClientPeg.get().getIdentityServerUrl();
         const loginType = "m.login.token";
         const loginParams = {
             token: this.props.realQueryParams['loginToken'],