No line connection through router

I got Dell Inspirion 5100 and Lyncsys WRT 160N Router. Wireless connection works fine. When I connect the LAN cable to the router’s Ethernet ports and my lappy, there is no light and no connection to the line. Message – your high speed internet cable unplugged.

When I connect my Inspirion directly to the DSL modem everything is OK. I checked and swapped all cables million times but got same result – it works from the DSL modem and not from the Router. The other laptop and other two desktops work fine from the same DSL/Router setting.

I am lost here. I don’t know what to blame here either the modem, my lappy or the router?

Anyone had similar problem and can explain what’s going on?