Nextcloud android client crashes on login

i have my oneplusx running on lineage 17.1, without gapps, Android nextcloud clients from Fdroid all crash when logging in with correct credentials, else it is just showing loginpage again. Iā€™ am using it in my local network only.
Nextcloud server is a new install version 13, access by desktop and bb10 (owncloud) works perfect. Access by owncloud client also works on my opx.

This looks like your problem. Correct me if Iā€™m wrong.