Reopening this discussion because I've learned something new about the topic.
Well ... it seems when I thought my issue had been solved when I posted some time ago that it had not.
And I have a clue to the behaviour.
I too have an external GB ethernet adapter / USB 3.0 hub. Using it to make a wired connection works fine, either from the USB port on the SP3 or from a USB port on the docking station.
If I use the ethernet port on the docking station while the USB ethernet adapter is connected to the dock (but not in use for ethernet connection) then the SP3 dock connects with no problem.
But, if I disconnect the USB ethernet adapter the docking station ethernet port then goes into the cycle of 'Connecting' ... 'Connected' ... 'Network Cable Unplugged' and no connection to the network is made.
So this is somehow related to having used the external USB ethernet before the docking station ethernet.
And deleting devices, reinstalling drivers, all those things have no effect.
A frustrating problem to be sure. Any suggestions welcomed!
It's definitely not a design error. I have installed 3 SP3s using MS docking stations & connected via Ethernet to our domain without a problem. I would be taking your docking station to the MS store and show them. They should replace it for free.
OK. A ways back on this thread when I originally had this problem, someone said "I have a bunch of these docking stations in service and have had no problems - return it and get a replacement, it's defective." (actually, I think it's the person posting above me saying for the second time "take it back")
I should have listened.
After my post above about it being the external USB ethernet adapter - I factory reset the SP3 (fourth time in three days) and reinstalled everything without ever connecting the USB ethernet adapter - and the problem came back!
Last Friday I bought another full SP3 setup - SP3, type cover, and docking station. It was being configured for another of my users but today, just on spec, I took the other dock and connected it to the same ethernet cable and port, dropped in my SP3 - and bingo, a solid connection.
Contacted a Microsoft Store rep on chat - they said "oh, only 30 days warranty on accessories, we can't do anything for you" but then suggested I phone technical support.
Tech support set me up with a walk in appointment at my local Microsoft Store (luckily there are two in the city in which I live) and my dock was exchanged for a replacement.
Returned to the office, connected the new dock, and immediately got another solid connection.
If you're struggling with the same issues of occasionally but rarely getting a network connection, you might want to consider whether there could be a few bad apples in the bunch of docks out there (and mine was from the original first release in August 14 but the replacement dock is from the same lot, 1433).
With any luck, this will be my last post on this thread!
I have been experiencing similar issue where my docking station Ethernet port would 'disconnect' periodically, generally every 24 hours. And the system event log would record event 16002 from source AFD -
"Closing a UDP socket with local port number 65015 in process 1456 is taking longer than expected. The local port number may not be available until the close operation is completed. This happens typically due to misbehaving network drivers. Ensure latest updates are installed."
Latest updates are installed automatically. I have applied "mareknereca" suggestion, reinstall gigabit ethernet drivers. We will see how this works.