Letsencyrpt setup fails for host with internal IP address

[Remah (Just another happy Discourse user)]

Let’s Encrypt needs to access the your IP address from the Internet.

The following topics/posts may help you:

Https with let's encrypt behind a vpn?

If your server isn’t publicly accessible then Let’s Encrypt can’t verify that the DNS name resolves. If it were possible for servers to get Let’s Encrypt certificates without first verifying this, then all kinds of mischief would be possible. Even if you can bodge this to temporarily get access and issue a certificate, it will fail for renewals. VPN can’t help you here. You’re going to need to either: ask your university if they operate a Certificate Authority and can issue the server a cer…

https://meta.discourse.org/t/adding-a-dns-name-to-an-ip-based-install/102898/2?u=remah

Using a certificate when Discourse is installed behind a reverse proxy

You’ve skirted around answering my question somewhat. Is there a valid public DNS record pointed at the public IP of the server? Are :80 and :443 externally accessible on that hostname and IP?