This used to happen to me with the same docking station, until it went away after some driver and firmware updates.  Is everything updated on your system?  Try looking for updates on the website, including this firmware update tool: <ADMIN NOTE: Broken link has been removed from this post by Dell>

Try looking manually as well as using your service tag

Yes, I have SupportAssist and I'm meticulous about having everything up to date. I've also updated the firmware of the dock, but the issue still persists. 

Funnily enough, it has started happening to me again too.  I can't pin down the exact circumstances. since it doesn't always occur.

Do you put the XPS to sleep before undocking?

Does it happen all the time, or some of the time?  Let's work together a bit to see what we can find out.

In device manager, I see the docking station Ethernet adapter when I show hidden devices.  Deleting it and rescanning doesn't help, nor hibernating or sleep and redock.  I recently reenabled fast startup in Windows settings  - do you have it enabled?

So, I am now being careful that the laptop is asleep before undocking, just close the lid, and wait until the docking station power light turns off.

Hasn't happened since then.  Might be a coincidence.,,,,