Nginx+Letsencrypt proxy subdomain

Hi all,

I have a nice little domain with a blog on the front page, secured with LetsEncrypt. So far, so good; but I like the domain I’m using so much that I want to point a subdomain at another service I’ve got running on a different IP.

I entered a new A record and added the following to my sites-enabled file:

server {
        server_name sub.domain.tld;
        location / {
                proxy_pass http://x.x.x.x:80;
        }

Then, I ran certbot and generated an SSL certificate for the subdomain without a hitch.

However, when I try navigating to https://sub.domain.tld, it will not connect at all; but using http:// works fine.

I’m not terribly experienced with Nginx and I’m afraid of losing track of changes and screwing up my config. Any advice?