I solved my problem. OK, like I said, I have an XPS 9333 13-inch.  It has 2 USB 3.0 ports, one on each side of the computer.  When I plug the dock into the LEFT one, my wireless connection stops working. When I plug the dock in to RIGHT one, my wireless connection works fine! I wonder if this might be worth a try for others.  It evaded me because of what I thought was the sheer illogicality of the notion that which of the two supposedly identical ports you were using would have an impact.   
hy, I just bought a XPS 12 and a targus docking station. I have the problem that whenever I plug in the docking station to the XPS the wireless connection becomes unstable and more often then not I cant connect to my wireless internet connection (the computer recognises the connection but then is not able to connect to it). As soon as I unplug the targus docking station, wireless works fine. I tried several driver updates as suggested in other posts but nothing seems to work. dziadgba
XPS 12, targus docking station, wireless problem