hmmmm
you tried phoneing ntl? they have a very good support desk.
when you say it stops working how do you get it working again? what lights on the router flashing not flashing?? also what lights flash and dont flash on the modem.
normally routers once configured unless they get a power surge or not setup correctly just run and do there own thing, if ever i have a problem with my ntl internet i restart my modem and then it runs fine.