If that is the SH1 - it should be replaced as soon as. Is it?
You could try the "free" SH1/2/2ac upgrade/replacement scheme - see the link below - as they are trying to get everyone onto Hub3's (may be a delivery charge). It works first time for about 50% of customers if it doesn't, come back here.
I do not work for VM. My 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 +2 Airport Express's. On VIVID200, Talk Anytime Phone, x2 Mobile SIM only iPhones.