If you look at the price of the Dock you could imagine that its running with limited capabilities - and one of these limitations is to have only one display cable connected. I was able to manage to connect a display on both, HDMI and DisplayPort,īut not simultaneously.
After some calls with Dell BIOS devs they really fixed my issue in BIOS Version A10 (see below) - BUT there are some limitations with the Microsoft DisplayDock which is not Dell's issue.