on 23-04-2013 23h17
See this post. It is a similar problem. The fix was changing the Homehub from version B to version A. Might be worth checking to see what version of hub you have and if need be see about getting it changed.
on 05-06-2013 21h57
Just stumbled upon this thread after searching on google. Just joined BT Infinity with a HH3 (Type A according to the admin page) and was having the same problems. All devices fine except my wife's IPad (her 4s was fine).
By switching the interface from b/g/n to b/g the problem went away. I'm puzzled but it solves it for now.
Hope this might help someone.