External monitor connection issues - strange behaviour

At first I didn’t think this was a docking station issue, but now I think it must be.

I’ve had the same setup for over a year: external monitor connected to docking station via HDMI. Recently, the monitor has intermittently not displayed the output from the laptop, but manually selecting the HDMI source on the monitor has fixed this.
However, for the past few days, I can’t get the monitor to display anything from the laptop via HDMI.
I’ve tried the following, with no effect:

  1. Changing the HDMI cable
  2. Clicking the ‘Detect’ button in the display settings
  3. Bypassing the docking station and connecting the monitor directly to the laptop
  4. Checking Device Manager – display adapter drivers are up to date

Now here is the strange thing that makes me think this might be a docking station issue, despite point 3 above. I can get the signal to display on the monitor via its VGA port, direct from the laptop’s HDMI port through an adapter. I can then also get the HDMI connection working, via the docking station. But if I then unplug the HDMI cable from the laptop, the signal from the docking station is lost as well.

I’ve tried uninstalling the DisplayLink graphics driver, cleaning and reinstalling as detailed here: https://support.plugable.com/t/driver-removed-by-latest-windows-10-update/17386/2

Do you have any suggestions?

Hi Paddy,

Thanks for posting!

Based off your results so far, at this point I’d like to request some logs from your system to investigate further.

Could you please keep the Plugable UD-3900 dock connected to your computer (with the non-working HDMI display still attached), then navigate to our PlugDebug tool and follow the instructions there?

This will create a ZIP file on your Desktop containing system logs and information. Please send this to us at support@plugable.com with subject of “Ticket #305003”.

Thank you for giving us a chance to help!


Thanks, Mitchell. I’ve just done that.

I look forward to hearing from you.


After receiving log files, we were able to see that external monitors were being recognized by the system, but were set to disabled. By following the steps below, we were able to restore the external display connected to the dock:

  1. Close or minimize any open windows
  2. Right-click on the desktop and select Display settings from the drop down menu
  3. Under Select and rearrange displays, select the display from the diagram that you are having issues with with a single left-click on the icon. You can click “Identify” to help you understand which monitor corresponds to which number label
  4. Scroll down to the bottom and select Extend these displays from the drop down under Multiple displays

I’ll be closing this thread, but for any other questions or concerns, please do not hesitate to open a new topic or reach out to us at support@plugable.com. We’re glad to help.

Best wishes,