Thank you for the link.
I’m currently trying to figure it out, but Plesk is a bit of a “I dominate this Server…with APACHE2!” thing and NGINX only runs as a reverse proxy.
/etc/nginx/sites-available/ is not even a valid path on my root, but /etc/nginx/ is.
I don’t know how much Plesk dominates everything.
I’m already asking myself, if I even can get Discourse running on a Root Server, which ran a plain ubuntu install first and then was entirely configured using the Plesk Web Installer 