I have a Dell E5540. I recently set up docking after having the dock for over a year. The issue I am having is that when the laptop is docked my wireless connection goes to almost nothing. Less than half a Meg.
When I pull it out of the dock the wireless jumps to normal. Reading on this issue I found a "workaround". If I open the lid on the laptop while its docked my wireless is normal...close it..and its back to zilch.
I would think this is a setting somewhere but, so far, nothing is working.
The Antenna for the wireless is located in the lid, so when it's closed, it's not receiving a good signal. Opening the lid exposes the antenna to more signal area to receive the wifi signal. Best way to resolve this is to use a wired connection when docked, or open the lid.