Your solution is in my message (10). If you want VM to resolve the issue call it in - it is a known bug with some ageing SH2's - they will simply send you a Hub3 replacement. This should be free so dont accept any charges and dont get talked into any upgrades you dont want.
-------------------- Services: HD TV on VIP (+ Sky Sports & Movies & BT sport), x3 V6 boxes (1 wired 2 WiFi,) SH2 in modem mode with Airport Extreme Router. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.