I ran into a problem. My password for registration had an "&" in it and i could connect via the app. After i changed the password everything works fine. So I guess there is a problem with special characters especially when connecting from the app to the server.
From XDA member otto.kranz:
I ran into a problem. My password for registration had an "&" in it and i could connect via the app. After i changed the password everything works fine. So I guess there is a problem with special characters especially when connecting from the app to the server.