I fixed my error. It was actually due to the domain name from SWAG (previously letsencript). Logs were throwing the error: "nginx: [emerg] "proxy_redirect" directive is duplicate in /config/nginx/proxy-confs/youtube-dl.subfolder.conf:22", which was solved by deleting that file. I guess SWAG was not even starting because of that error so custom domain names do not work.
Hopefully this helps someone.