Flashing green light often means that the new Hub is not "activated" onto your account. Is it a new "quickstart" connection - or just a Hub swap?
Call the equipment activation number on - 0800 953 9500 – you will need the serial number/MAC address off the barcode sticker and also your account number, Call now but at 08.00 (Mon-Sat) or 09.00 (Sun) for the best chance of getting through quickly.
If they insist it is activated then there may well be a fault on the network connection. VM never check the connection quality - they assume all is fine as they know there was an active connection at the address before.
You will need to call the fault line in that case. A VM person will help here but they can take a couple of days to get here
--------------------
John
--------------------
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.