After reading this thread, I finally got it working. In my set up there are no Pan or Zoom controls. Just views of the various IP cameras. So I did a port forwarding set up using the IP address of the NVR with port 80 for both external and internal ports on a TCP protocol. Saved settings and on my PC browser. I did a <canyouseeme.org> and checked for a Successful result for port 80 with the detected IP address of my WAN internet connection. This confirmed for me that any external request for connection (with proper login credentials) can see my NVR port. Tried with phone on mobile data (WiFi OFF) with the App and obtain a successful online connection. I can a peaceful sleep tonight.
