SSL Self-Signed Certificates Issue

Hello everyone,

It is the first time that i actually write here and I’dont know if is the correct section.

I have a Gitlab Community Edition (17.2.1) via omnibus metod, installed and running on my Linux Server.
The issue is that on my machine (100.X.X.X) is reachable also with an external address (i have a router that sends with another IP in a different network) and also a Proxy DNS for external. How i have to properly set for all of this configuration the correct function of Https with self-signed certificate? I need a solution also for an alternative install of HTTPS for the addresses or only on the machine?

Thanks!