<<< I have tried already and there is an uplink but no down link. >>>
An "uplink" on what - the router?
Network "switches" often have an Uplink port which is used to connect additional "switches" in order to daisy-chain them and provide additional ports. The effect of using an Uplink port, instead of a standard port, is exactly the same as changing between a "straight-wired" ethernet cable and a "crossover" one.
If the "Uplink" port is at the back of the PC, are you sure it isn't the modem card which has a "pass-through" port so that a phone can still be connected?