TBT4-UDZ - Both Display Ports Not Working

Both displace ports on the docking station is not work. I’ve tried hooking the station up to both a Mac and a PC. HDMI ports work fine, nothing from the display ports.

Hello,

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

  1. How many total monitors are you trying to use through the dock?

  2. What model Mac system and also what brand and model PC do you have?

  3. What brand and model monitors are being connected to the DisplayPort outputs that are not working?

  4. Are you using standard DisplayPort to DisplayPort cables or is there any kind of adapter in use?

  5. When the DisplayPort outputs are not working, is this with or without the HDMI outputs also connected?

Once I know more about your setup I can hopefully offer some suggestions.

Thanks again for contacting Plugable support and best wishes!

Joshua Henry
Senior Engineer | Product Owner
Plugable Technologies

  1. How many total monitors are you trying to use through the dock?
    A: 3
  2. What model Mac system and also what brand and model PC do you have?
    A: Mac is 16" MacBook Pro 2021 w/ M1 Chip, HP EliteBook 840 G6
  3. What brand and model monitors are being connected to the DisplayPort outputs that are not working?
    A: LG 25" Ultrawide IPS LED - 25UM57-P
  4. Are you using standard DisplayPort to DisplayPort cables or is there any kind of adapter in use?
    A: HDMI to DisplayPort w/ HDMI Elbow Adaptor
  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.

Thank you for this information!

Unfortunately, neither of your systems are fully compatible with this dock for the full multi-display features the dock can offer.

  • Apple M1 non-Pro/Max processor based Mac systems are limited to a single display maximum, M1 Pro/Max can support two displays maximum. Greater than two displays using Thunderbolt over a single cable to a dock like this is not possible due to Mac chipset limitations. So your Mac will be limited to one or two displays only depending which version M1 you have (M1 vs M1 Pro/Max).

  • Your HP EliteBook 840 G6 is only Thunderbolt 3 and not Thunderbolt 4/USB4 looking at the HP specifications. As such is also limited to a maximum of two displays (due to Thunderbolt 3 limitations).

  • Finally, converting DisplayPort to HDMI will not work unless using an “active” adapter. If the adapter you used did not work with the other HDMI monitors disconnected then I expect it’s because the adapter is “passive” which is not supported.

Unfortunately I suspect that this dock will not be a good fit for your needs unless you can use it for just the two displays.

We try to call this compatibility information out in-depth in our website knowledgebase, however, we understand if you had not seen this information prior to purchasing the dock: https://kb.plugable.com/question/1705024

For your two computers we offer a different dock that could enable up to three displays which may be a better choice: http://plugable.com/products/ud-ultc4k This dock uses a combination of USB-C and DisplayLink USB graphics technologies to work around the limitations over Thunderbolt for your two systems.

If you have any questions or concerns please let me know.

Best wishes,
Josh

I am having the same issue with neither DisplayPort connections working. Their are no adapters and I’m using a Surface Laptop 5. The monitor is an older Dell P2214Hb. Is there something in this setup that isn’t compatible?

@jack3 Thanks for contacting us! Sorry to hear about this issue with the DisplayPort outputs not working.

Your Surface Laptop 5 should offer 1x USB-C with USB4/Thunderbolt 4 support per the Microsoft specifications, so it’s odd that your system would be encountering issues with the DisplayPort outputs.

We have not yet tested the TBT4-UDZ with the Surface Laptop 5 so I unfortunately cannot confirm or not if this is an expected issue for this model system. On paper I would not expect for there to be issues, however, we could be running into some kind of incompatibility (earlier Surface models have had some limitations with how USB-C/Thunderbolt has been implemented but not where the DP outputs were not functional).

How many monitors are you trying to use in total? And may I assume that if trying the Dell P2214Hb by itself with no other monitors attached also does not work?

Finally, for this issue I would like to get some additional data to help find out what could be causing this problem. 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 the Dell monitor attached to it into your computer, then go to this page and follow the instructions there:

http://plugable.com/support/plugdebug

Please email us the diagnostics results to support@plugable.com and I can then take a look for any clues from a software perspective and hopefully offer some suggestions. Please do not post the diagnostics results here!

Thank you and best wishes,

Joshua Henry
Senior Engineer | Product Owner
Plugable Technologies
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I am trying to connect 3 monitors in total and you are right that the monitor doesn’t work by itself with nothing attached. My surface is recognizing that monitors are attached, but nothing is actually displayed with the DisplayPort connection.

I went out and bought a new monitor and that solved the problem so I am thinking this has something to do with the older monitors. I’m going to skip the debug for now since I’m up and running.

Thanks!