I went away for holiday for a week, we had no issues with the internet and Home Hub 4, apart from the wireless signal being pants and keep on disconnecting now and again.
I came back of holiday and powered everything back up. and for some reason the internet was down, so I reset the router. Bing works fine, but now certain programs keep registering a disconnection. (lastpass googlemail etc) so I checked the router logs and I was getting errors on port forwarding. Intrigued, I phoned up the customer support, and after the standard line checks, restarts etc, they requested for me to change the router and see if the problem still occurred. As luck would have it I still had a home hub still brand spanking new in its packet from the new contract we just set up. I had no reason to ditch the old modem/router as it was fine. So i unwrapped it from its packet and plugged it all in. Bearing in mind this router is fresh from the factory, has no pre set up port forwarding etc. The old router did have some port forwarding on uit for various online games / programs etc. Still the same problem!
Googled my issue and the first thing on the list was BT Openreach and various other people having exactly the same issue So, basically, i am assuming there is a problem with the cabinet or someone has pressed a button wrong somewhere on their server to cause these problems
Here are some screen shots of my router. please note there is a shot of the port forwardings, just to point out I have not changed anything.