Apple TV does not appear in devices in iTunes-Using BT home hub 2

Hi, I previously used a BT Home Hub 1.5 and occasionally had problems syncing to iTunes. Updates from Apple sorted this. I recently moved to BT Home Hub 2 and again all was well for several days. I have not changed any settings, however suddenly Apple TV disappeared from the iTunes device list. I have reset the Apple TV to factory settings, it can connect to the internet ok, but cannot connect to iTunes on my mac (via wireless). They are in different floors of the house so ethernet is not easy. I have tried without success to play around with the application sharing settings in the advanced area of the Home Hub, (apple TV does not appear as a device) so one has to create one but cannot follow exactly what to do. I assume others also have this issue?
Any advice most welcome.
Phil