You need to use the correct port otherwise your router will not work so make sure it looks like the picture below as the only port now live is the one next to the power lead and the other 3 are disabled.
Modem Mode Help
Modem Mode
When active, Modem Mode disables the wireless and routing functions of your Super Hub so you can use your own wireless router.
For more information please visit <
http://www.virginmedia.com/help/>
Active Ports & Connections
When in Modem Mode, only one Ethernet port will be active on your Super Hub. You can connect a PC/laptop/console etc directly to your Super Hub via this active port. The image below highlights the port that should be used to connect your external equipment.
Disable Modem Mode
You can disable Modem Mode from the Main Menu which is accessed by typing 192.168.100.1 in your internet browser.
Alternatively you can restore your Super Hub back to its original settings by using the reset button on the side of your Super Hub.