Fido 2 not working on self hosted install

I have a self hosted server that is accessible via a local IP Adress rather than a domain name.
When I try to register a Fido2 key I get an error Message that the key could not be read. I set up another server instance with a domain name for testing and that seems to work just fine.
Is there any reason for this behavior (is this expected) or is there a workaround / am I missing something?

The server has a valid SSL Cert and everything else works fine.

Thanks!