TBT3-UD1-83 Thunderbolt 3 dock - iMac with 4K via DP++ intermittent loss of picture

I have a TBT3-UD1-83 dock plugged into an iMac 5K (2017) running High Sierra. My setup is a triple monitor configuration with 2 additional BenQ BL2711U 4K monitors. One of the BenQ is plugged direct into a TB3 port at the back of the iMac. The other BenQ is plugged into the dock’s DP++ port. The dock is connected to the second TB3 port at the back of the iMac.

Note that I also have an external USB 3.1 hard drive enclosure plugged into the second TB3 port of the dock.

For the most part everything works great. I can get a proper 4K/60Hz picture on the second BenQ via the dock. However I get an intermittent issue whereby the screen will go black (i.e. picture disappears) for a couple of seconds before returning. It’s like a momentary flicker that lasts for a couple of seconds or so. It happens intermittently - maybe once or twice a day.

I’ve swapped out the DP-to-DP cable but the issue reoccurs. Just in case it might matter, I have one of your 10 port USB3 hubs sitting on top of the dock.

Note also that I don’t have this issue with the first BenQ that is plugged directly into the first iMac TB3 port (via one of your USB-C to DP cables!).

Any ideas?

Hi Martin,

Thanks for posting, and I would be happy to help you with your docking station!

Thank you as well for the excellent detail you provided, that is most appreciated. The behavior you describe is not expected, so our next step is to get some additional information to help determine the next steps.

If you would, while everything is connected please send a System Report (instructions below) and your Amazon Order ID number (available from amazon.com/orders, please don’t post it here in the forum) to support@plugable.com with ‘For Ticket #205279’ in the subject line so we can match everything up.

Thank you for giving us the chance to help!

Plugable Technologies

System Report Instructions:

  1. Choose the Apple Menu -> About This Mac.
  2. From the window that appears, click on the ‘System Report’ button.
  3. A System Information window will appear. From the application menu bar, click on File -> Save… to save the information to a file
  4. Attach the saved file to your email to support@plugable.com