If it was a certificate issue I’d expect youd just get an error from your browser saying the cert is invalid or expired.

If I had to guess though you’re running into a nat reflection issue: https://nordvpn.com/cybersecurity/glossary/nat-loopback/

Read up on that. But you may need to provide different DNS entries if you’re inside or outside your LAN or add a NAT hairpin rule to your router. But this is only applicable if you’re exposing the same service to the WWW.

Some other things to try though:

• Have you tried just pinging the address? Is the DNS resolution returning the address you expect?
• Whats in your nginx logs? Do you see anything when you try and connect?
• Within your nginx container can you ping your service directly? Is something blocking nginx from accessing the site?

Because of changes in how the lemmy API works I had to abandon the project awhile back.

The GitHub page is still up and if anyone wants to take over they’re more than welcome. But the project would need a complete rewrite in order to function and even then there’d still be limitations.