debian\ubuntu vm on proxmox. Then you can snapshot the whole deal and take easy backups of everything using proxmox backup server.

The issue could still be a fail-to-band issue if fail-to-band is looking at the user agent string (I’m not sure fail to ban looks at the user agent string, but it might be worth checking out.). The user agent string would likely be different on a mobile app versus a browser login.

Nextcloud maps works reasonably well although mobile view isn’t great.