Unable to View CCTV Remotely

[#1]

My friend switched to Plusnet 3 days ago from BT. I setup his router for port forwarding for his CCTV setup exactly same as with the BT router.

He now has a very strange issue that he cannot view his CCTV remotely while on 4G with o2, I tested with my Three mobile and also a Vodafone one and this works absolutely fine. We then tried another mobile that was on o2 and the same issue occurred. 

This used to work flawlessly while with BT.

Anybody else experienced this or any ideas?!?

[#2]

@Lou1875 

I can't answer your question but would suggest that you reinstall the BT Hub and see if that works. They are much better devices anyway and may of us use a Smathub 6. You will find setting instructions for connecting to Plusnet pinned ar the top of this Router board.