Router disconecting after random minutes

[Flame]

I set a router up at a friends house, i got it all working with the laptop and my iPhone and on the actually wired computer. My problem is, the router randomly disconnects from the internet, after a few minuets or could take unto 30 minutes the internet connection will come back and will work for so many minutes then it will all go down again. Ive checked the Idle/Lease time and its not that...

There with Tiscali if that makes a difference.

Any help is greatly apreciated