loadbalance.conf

user www-data;
worker_processes auto;
pid /run/nginx.pid;

events {
        worker_connections 768;
        # multi_accept on;
}

http {

    upstream myapp1 {
        server 128.199.223.229:8080;
        server 128.199.224.175:8080;
        server 128.199.224.194:8080;
        server 128.199.210.95:8080;
    }

    upstream myapp2 {
        server 188.166.238.138;
        server 188.166.229.175;
        server 188.166.228.182;
        server 188.166.226.159;
    }

    server {
        listen 81;

        location / {
                proxy_pass http://myapp2;
        }
    }

    server {
        listen 80;

        location / {
            proxy_pass http://myapp1;
        }
    }

}

Thank you