Nginx Server-block for Reverse Proxy for Plex in OpenMediaVault to place in /etc/nginx/sites-available/.

openmediavault-plex

server {
    listen [::]:443;

    server_name plex.mydomain.com;

    rewrite     https://$host$request_uri?  permanent;

    error_log   /var/log/nginx/openmediavault-plex_error.log    error;
    access_log  /var/log/nginx/openmediavault-plex_access.log   combined;

    ssl on;
    # These are the paths to your generated Let's Encrypt SSL certificates.
    ssl_certificate     /etc/letsencrypt/live/plex.mydomain.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/plex.mydomain.com/privkey.pem;
    # To generate your dhparam.pem file, run `openssl dhparam -out /etc/nginx/dhparam.pem 2048` (without the quotes) in your terminal.
    ssl_dhparam         /etc/nginx/dhparam.pem;
    ssl_session_timeout 1d;
    ssl_session_cache   shared:SSL:60m;

    location / {
        # IP address of Plex Media Server
        proxy_pass          http://127.0.0.1:32400;
        proxy_buffering     off;
        proxy_redirect      off;
        proxy_http_version  1.1;
        proxy_set_header    X-Real-IP       $remote_addr;
        proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header    Upgrade         $http_upgrade;
        proxy_set_header    Connection      $http_connection;
        proxy_cookie_path   /web/           /;
        access_log          off;
    }
}