You need to add the information to your nginx configuration, for it to route the traffic.

server {
  listen 80;
  server_name  example.org  www.example.org;

  # Reverse Proxy
  location / {
    proxy_pass http://localhost:$PORT;
    proxy_set_header Host               $host;
    proxy_set_header X-Real-IP          $remote_addr;
    proxy_set_header X-Forwarded-For    $proxy_add_x_forwarded_for;
  }
}

That’s an example config. You’d need to have two Server blocks, one per port. The proxy_set_header might not be needed, I’m just copying an old config I used.

If both apps use the same domain (or IP), you can just have in the same server block, two location blocks. For example.

  # Reverse Proxy
  location / {
    proxy_pass http://localhost:$PORT;
    proxy_set_header Host               $host;
    proxy_set_header X-Real-IP          $remote_addr;
    proxy_set_header X-Forwarded-For    $proxy_add_x_forwarded_for;
  }

  location /nodeApp {
    proxy_pass http://localhost:$PORT;
    proxy_set_header Host               $host;
    proxy_set_header X-Real-IP          $remote_addr;
    proxy_set_header X-Forwarded-For    $proxy_add_x_forwarded_for;
  }
}

The latter, will allow yo to have example.org go to WordPress for example, and example.org/nodeApp to the Node.js app.