If your address shows Welcome to nginx! and "If you see this page, the nginx web server is successfully installed", your server is running but it is not serving your site.
nginx is the web server program. This is the default page it shows before anyone configures it. Usually one of three things happened: a new server was set up and the site was never pointed at it, the server was rebuilt or updated and the site configuration was lost, or your domain now points to the wrong server.
dig +short yourdomain.com or use any online DNS lookup. Compare the address with the server you expect.sudo nginx -T | grep server_name. Your domain should appear. If it does not, the site configuration is missing or disabled./etc/nginx/sites-available/. If your site file is there, link it into sites-enabled, then run sudo nginx -t and sudo systemctl reload nginx.default site if it is catching your domain first.Send them the exact message and the time you saw it. It is a configuration problem, not a hack, and a competent admin can fix it in minutes.
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