Can't connect to self hosted server

For a few days now, I have been unable to log in to my self-hosted server on my network with my desktop app and the mobile app. I always get the error message “Failed to fetch”.

I also have a browser extension on the same computer as the desktop app, but this can connect and synchronize. I can also reach the server from any device at https://10.10.1.80 or https://bitwarden.lan without any problems, so it can’t be due to any network restrictions.

VERSION
Server Installed
2024.5.0
Server Latest
2024.5.0
Web Installed
2024.5.0
Web Latest
2024.5.0

Does anyone else here have an idea what I can check?

Thanks in advance