TBT4-UDZ not outputting via display port


I am trying to set up my TBT4-UDZ and having issues outputting to 4 displays

  1. How many total monitors are you trying to use through the dock?
    A: 4, the two HDMI monitors are working, the two Display port monitors are not
  2. What model PC do you have?
    A: HP EliteBook 840 14 inch G9 Notebook PC, 12th Gen Intel(R) Core™ i7-1265U, 1800 Mhz, 10 Core(s), 12 Logical Processor(s)
  3. What brand and model monitors are being connected to the DisplayPort outputs that are not working?
    A: Asus VN 279 1920 x 1080
  4. Are you using standard DisplayPort to DisplayPort cables or is there any kind of adapter in use?
    A: I have tried both Display port to display port as well as a display port to HDMI (in on the monitor) cable
  5. When the DisplayPort outputs are not working, is this with or without the HDMI outputs also connected?
    A: I tested it both ways. Nothing worked.

Are the monitors that I am using the Display Ports on need to support Display Port 1.4?


These are the specs of my laptop

A post was split to a new topic: TBT4-UDZ Multi Display Issues

Hello Rick,

Thank you for contacting Plugable support! Sorry to hear about this issue. I’d be more than happy to assist you.

I would proactively suggest to ensure you’ve got the latest BIOS from HP installed as I see the newest version for your HP EliteBook 840 14 inch G9 offers quite a few possible fixes in the release notes: https://support.hp.com/us-en/drivers/selfservice/swdetails/hp-elitebook-840-14-inch-g9-notebook-pc/2101000805/swItemId/ob-304684-1

Also, please note that when using this dock it cannot support the DP to HDMI adapter cables you’d tried (unless they’re specifically “active” adapters, as passive adapters aren’t supported). So I’d recommend to use the DP to DP cables only for the second set of monitors.

For the next steps we have a troubleshooting tool that helps us find out what is going on in situations like this. If able, please plug the dock with your quad displays attached to it into your computer, then go to this page and follow the instructions there:


When emailing us the diagnostics results please mention ticket number 402621 in the subject line so that we can match those files to this case. Do not post the diagnostics here!

I can then take a look for anything in the diagnostics results that stands out for this issue and offer some recommendations for next steps.

Please don’t hesitate to let us know of other questions.

Thanks again for contacting Plugable support and best wishes!

Joshua Henry
Senior Engineer | Product Owner
Plugable Technologies

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