I moved to a new server and reinstalled Jitsi there.
I have split the server into vServers via Proxmox, Jitsi is a separate vServer. The server has an IP address that points via pfSense to the Nginx Proxy Manager, which splits the requests to the different vServers.
Now I get when calling my Jitsi instance but the message Uncaught ReferenceError: interfaceConfig is not defined and do not quite understand why.
I forwarded the necessary ports to the vServer via pfsense.
Also, the Jitsi server is running a nginx and the Nginx Proxy Manager forwards to port 80.