I have installed a fresh docker image of nextcloud 12.0.3 and tried to connect with the anroid 2.0 app to this instance.
After asking for “grant access” and adding the username nad password a screen after a while a screen appears which states redirect (“weiterleiten” in german) and the spinner turns for ages.
It is the same behaviour when I try to connect via my nginx revers proxy (using https) or going directly to the server (via http).
The login to the web client works as well as the windows desktop client.
Any Ideas where I can search for the problem?