How all the same to receive the certificate without 80 and 443 ports?

Question

linux

According to this article https://blog.hostonnet.com/install-letsencrypt-ssl... , I'm getting a great certificate. With the condition that ports 80 and 443 are not used. And everyone writes that it is necessary to open ports 80 and 443 mandatory. Although, again, the Proxmox server works behind NAT, so opening port 80 is in principle possible, but only on the local network.
Tell me all the same how to get a certificate when using a web server other than 80 and 443 ports?

Answer 1

You can get a certificate on another server, even on the cheapest VPS, and then transfer the certificate to the desired machine within the network.
The certificate is not bound to IP addresses in any way, but is bound only in the DNS name.