A typical Nginx server block for Webmin.

example-nginx-webmin.conf

# A typical Nginx server block for Webmin.
# This asumes that you have disabled ssl in webmin miniserv.conf and added 
# referer=manage.example.com in webmin conf file.
# Author: Mikael Luxwarp Carlsson luxwarp@codeiolo.org https://codeiolo.org
# License: ISC
# Created: 2019-08-22

server {
    # Ports to listen to.
    listen 80;
    listen [::]:80;

    # Server name to listen for.
    server_name manage.example.com;

    # Proxy down traffic to running webmin server.
    location / {
        # set some headers and proxy stuff.
        proxy_pass http://localhost:10000;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

        # include Host header
        proxy_set_header Host $http_host;

        # Fixes initial redirect after login
        proxy_redirect http://$host:10000/ https://$http_host/;
    }


    # Where to store logs for nginx traffic.
    access_log /var/log/nginx/manage.example.com.access.log;
    error_log /var/log/nginx/manage.example.com.error.log;
}