Thanks for your response Ron
There is nothing obvious (to my eyes anyway).
I have emailed BT to see if they can advise on the settings of the Home Hub, but I have given up on Belkin, communicating with them is impossible.
Might be worth checking for firmware updates — likely others are having the problems too.
Might be that they have been shamed into fixing it from a barrage of questions from users. 🙂