Ethernet Port Not Working on Docking Station

I have a Dell e5540 with matching docking station ( Dell E-Port II).  Ethernet signal and internet connection will work going directly into the computer, but will not work when plugged into the docking station.  I  have gone at lengths to get a new docking station, and it still does not work.  I have spent several hours on the phone with dell customer support and have not received any resolve to this issue.  Do you have any suggestions?