This is the nginx.conf file for my external proxy:

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;

    server_name ;

    include /config/nginx/ssl.conf;

    location / {
        include /config/nginx/proxy.conf;
        include /config/nginx/resolver.conf;
#        set $upstream_app lemmy;
        set $upstream_app proxy;
        set $upstream_port 8536;
        set $upstream_proto http;
        proxy_pass $upstream_proto://$upstream_app:$upstream_port;
#        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header X-Real-IP $remote_addr;
#        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        client_max_body_size 50M;            
    }
}

access_log /var/log/nginx/access.log combined;

You’ll need to change  to the appropriate value. I’m forwarding requests to the proxy container referenced by the compose file