Nextcloud Android App 3.16.1 - Timeout editing files

Hi everbody,
i have a strange behaviour with my nextcloud instance and the android app.
When i login / connect the app with my nextcloud instance, i can edit text files within the app. After some hours or perhaps a day i only get an timout, but everything else (Upload, Download,…) is working correctly. When i delete my account from the app afterwards and reconnect/login again, everything is working correctly for some hours. Then the same error occurs again.

My Environment:
Samsung s8, Android 9, nextcloud App 3.16.1. also tested on Android 10/Samsung a51 - same error.
Nextcloud Server 21.0.2 running on docker host (x86), used example:, certififacte self-signed

Are there any known issues or some hints to fix this timeout? Or can i assist with further data?

Kind regards