Phil

Turn Modem and Router off.
Plug Ethernet cable from Router to PC and Turn router on.
May as well turn modem on so it picks up an IP address from NTL.
In a browser, browse to your router using IE or Firefox address is something like http://192.168.1.1 (will be in your manual)
Enable wireless (dont bother with security as yet)
save settings and turn router off.
plug the ethernet cable into your modem/STB then to the router and switch it on.
Wait for about 2 mins.
Make sure wireless in running on your PC/Laptop and try and connect to the internet using wireless.
If this works, you will then need to set the wireless security up.