// 12. Feb 2025, problem lasting for at least a week now.
// Everything else seems to be working.
// Nothing new there.
Nextcloud 30.0.5
Debian 12
Proxmox
VPN: Zerotier
Any idea? 
// Nothing new there.
You seem to have deleted the support template. You will likely find clues about the cause if you fill it out… particularly the Web Browser section.