IP camera - enabling access from WAN

[#1]

I have a Supra IPC-1 security camera on a fixed IP of 10.131.97.195 connected wirelessly to a Netgear DGN2200 router, which connects to WAN via Plusnet as ISP.

The camera works fine if accessed via my LAN, but I now have no access to the camera from the WAN, since swapping the router to the above item. The previous router turned out to be faulty. The problem is something to do with Port Forwarding, of that I am fairly sure, I have set up on the router to forward port HTTP(TCP) 80, to 10.131.97.195.

Using my Three mobile (MiFi) access point, combined with a laptop - I get a 504 gateway Timeout error when I try to browse to the camera's web page.

The server did not receive a timely response from the upstream server specified by the URI.

This is mcihttpd/1.1 (MegraCloud infrastructure http daemon) on dynamicdns.megracloud.net.
(C) 2013-2017 supra Foto-Elektronik-Vertriebs-GmbH.

I appreciate my WAN connection via Plusnet is not a fixed IP, but my system used to cope with that via the camera manufacturers website with some wizardry - my guess is the camera regularly reports its WAN IP back to their server, then when I try to access my camera the server redirects me to the correct WAN IP. What I also cannot be certain of, is the Supra sIte redirect server still operational?

Any help appreciated please..

[#2]

Update - I have managed to log into the dynamic IP server manually and it is reporting my correct Plusnet WAN IP, so the request is probably not getting through to my camera.

Update on my update - No it is not, it is reporting a wrong WAN IP, but even typing my correct WAN IP in followed by :80 I am not accessing my cams log in page.

I can successfully ping my correct WAN IP, from inside my LAN.

The server is this one - http://legacyadmin.supracam.net/User/Index.aspx - supra DynamicDNS

It is presently reporting my IP as-

143.159.57.78:80

Dated 3/20/2017 1:19:07 PM

Which was around when I swapped my found to have a fault router, for a replacement.

My actual WAN IP is - 51.7.67.16

[#3]

I set up a second account with the Dynamic IP server, on testing that, it is reporting my IP as 0.0.0.0