diff --git a/user_manual/groupware/sync_android.rst b/user_manual/groupware/sync_android.rst
index c85e1c2a6..509d4758f 100644
--- a/user_manual/groupware/sync_android.rst
+++ b/user_manual/groupware/sync_android.rst
@@ -72,4 +72,9 @@ steps are required:
    account using the Nextcloud mobile app, this all should be aready the case.
 
 
+.. note:: Using user name and password will not work if 2-Factor-Authentication
+   is enabed and will throw a generic "Unknown resource" error.
+   Use a dedicated App password instead.
+
+
 .. tip:: DAVx⁵ lists the calendar subscriptions made through the Nextcloud Calendar app, but you need to install the `ICSx⁵ (formerly known as ICSDroid) <https://icsx5.bitfire.at/>`__ app on your Android device, `from the Google Play Store <https://play.google.com/store/apps/details?id=at.bitfire.icsdroid>`__ or `from F-Droid <https://f-droid.org/packages/at.bitfire.icsdroid/>`__ to sync them.