Ok, found it.  Apparently the docking station isn't capable of 4K video output.  I have to use the HDMI port on the laptop instead.  Thus rendering the docking station far less useful.
I've just gottten a Dell 3571 with a WD19DC dock.My monitor is a 4K large screen.  Display resolution is at 3840x2160The Win 10 background image is crisp and clear.The text in all apps is chunky/blurry.How do I make it legible?
Fuzzy/Chunky text on 4K display with crisp clear background