I don't have a computer that can be wired via the ethernet. I'm due to receive the new Hub 5 next week so I'll await that before doing any further tampering.
However, everything worked fine before the V6 box upgrade so I'm at a loss as to why this fault has suddenly reared its head.
Online chat with customer services revolved around switch it off and back on again which proved utterly fruitless.
If it comes to it, I'll have to downgrade back to a V6 box as the 360 is unwatchable at the minute.