Just in case anyone is having issues getting Ethernet to work in a docking station, I just had this happen and found the player just needed to be pulled from the docking station and put back in a little "harder" than before.... now all is well. I guess the ethernet connector wasn't fully plugged in while the other docking connector was.

I might drill a hole in the back of my docking station so that the blue light can shine through to make this easier to diagnose.