I have a BT HomeHub 5 Type B and a few months ago, the firmware updated to v0.07.05.0A13-BT which caused the WiFi on my router to completely mess up. The speeds are slow and it's very intermittent so it's fast only sometimes. I am pretty sure it was due to the update. I am wondering if there is a newer firmware version? I realise that I'll have to wait for the update but if there isn't then I'm considering getting a new router. I have a Type A Hub 5 too but that caused me a lot of WiFi issues (not sure if that has been fixed) and yes I fiddled around with the channels etc.
it's some routers don't do channel 13 not devices hence why sugegsted as may cut channel congestion