If you use any other domain name, Caddy will attempt to get a publicly-trusted certificate; make sure your DNS records point to your machine and that ports 80 and 443 are open to the public and directed toward Caddy.
First OP needs to configure his DNS service.
Then he needs to port forward 443 (if I’m reading the instructions correctly).
Okay this is neat, but still:
First OP needs to configure his DNS service.
Then he needs to port forward 443 (if I’m reading the instructions correctly).