Plugabke UD-3900Z Dock

New dock, two HP monitors, one flickering. If I switch hdmi ports the flickering monitor works and the other then does not. Uninstalled and reinstalled drivers, no luck. Updated windows software; no luck. Any ideas how to fix this?

Hi Jason,

Thank you for contacting Plugable! I’m sorry that the UD-3900Z isn’t working as expected, and I’ll be happy to assist.

Based on your description of the behavior it sounds like the flickering issue is isolated to the HDMI port on the UD-3900Z. Our next step is to get some additional information.

Can you please send an email to our direct support email address ( with “For ticket # 411603” in the subject line? In the email please include:

  1. The Amazon/Walmart/Newegg/eBay Order ID number for your UD-3900Z purchase. If you bought it from Amazon this information is available here:

  2. While the UD-3900Z is connected to your PC with the displays plugged in (even if not working as expected), the output of our diagnostic utility PlugDebug:

  3. The HDMI ports on the back of UD-3900Z are labelled as “HDMI 1” and “HDMI 2”. Can you please indicate which of these ports the flickering monitor is connected to?

This information will help us to determine the next steps.

** Please do not post the above information here in our public forum (it contains personally identifiable information) **

My apologies for the frustration, and thank you for giving us the chance to assist!

Plugable Technologies

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