I had the original wireless box 1 until a few days ago, which was fine on wireless (I only use a phone wirelessly - pc is wired). Because of a speed issue and others, o2 changed my box to a V. Speed is now near where it ought to be for my line. I turned on wireless, paired my phone to the router with the SSID and key and all seemed fine.

But wifi kept stopping despite giving the appearance of still being connected ok. I called o2 and they changed the channel from 1 to 13. This seemed better initially but soon proved the same. I called again and they were not able to log onto my router to make any changes but recommended I tried 6,7 or 8. I tried 6 and seemed better but still disconnected as did 7 and 8. They told me that box 5 was proving problematic and they may have to send me out another, either a 2 or 4. I have since downloaded an app to my phone that picks up the local wifi networks so have set channel to automatic selection to see what happens. Here is a shot. It's sent from the mobile so will be a bit dinky. Mine is the blue curve in the middle.

I don't know much about wifi, but all I know is the old router was fine in that respect. It has an antenna whereas this new one has none. AFAIK the other o2 boxes have antennas. Not sure what effect that has.