Well, at this moment thanks to this tutorial I managed to configure Nginx correctly and now when I go to the subdomain of my website, everything works perfectly.
What the tutorial does not mention is how I can add a second domain in the /etc/nginx/sites-enabled/mydomain file since at the end of the tutorial the document already has an SSL certificate that points to a specific IP address and domain.
I have read that it is as simple as "copy and paste below the “server” block but in that specific example there are two server blocks, and if I try to create another file using the same content of that one but changing the IP and subdomain, I get an error when trying to restart Nginx saying there can’t be two files pointing to ::[80]:
Sorry didn’t read your post entirely before I answered. Are you trying to have a second separate site, or just an alternative domain pointing to the same site?
I am trying to have a separate second site.
https://stackoverflow.com/questions/68196179/how-to-create-reverse-proxy-for-multiple-websites-in-nginx