Dock Fails to Connect on Boot

Admittedly I am using Linux primarily with this dock. It works perfectly on a hotplug. It works perfectly when the dock is power cycled. On reboot it causes issues and fails to show as being connected though power delivery works. On a cold boot it fails to show as being connected however power delivery works. Power cycling the dock brings everything online. I have never seen this behavior with any dock. Very odd. Regardless any suggestions as to a potential cause would be appreciated.


Thank you for contacting Plugable support! Sorry to hear about this issue. I’d be more than happy to assist you, although to be fully up front at this time we do not officially support Linux with our Thunderbolt docks, like your TBT4-UDZ.

Thus far we haven’t performed any in-depth Linux testing to know if this may be more of an isolated issue between the dock and your particular system model, or if there is a larger compatibility problem between the dock and say a driver or other aspect of the Linux kernel.

To help understand why these issues may be occurring may I trouble you for some additional information?

  1. What brand and model system is the dock being connected to?

  2. What Linux distro and version are you currently running?

  3. I am uncertain if you are running another OS on your system, but for example if running a dual boot with Windows, I would be curious if the behavior persists there as well. (If that’s not an option to test, no worries.)

  4. I also just want to verify that you are indeed using our provided Thunderbolt 4 cable the dock shipped with. I ask as if using a different cable it could cause the dock to behave unexpectedly under certain conditions. (Although since it works fine for a hot plug I anticipate you’re most likely using our provided cable.)

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

@Joshua_H sorry to waste your time with this. I decided to return the dock rather than spend what would likely be countless hours trying to get it to work correctly. I am just going to order a hub since I have confirmation those work with the laptop, and with Fedora. Regardless I will answer the questions:

  1. The Laptop is a Framework with an Intel I7-1260p running the latest BIOS whihc passed the Intel Thunderbolt Certification.
  2. Fedora 37
  3. No other OS on the laptop, I was considering dragging out a Windows machine I keep for testing, but since that has Thunderbolt 3 I did not feel it was a solid option for direct comparision.
  4. I was using the provided TB4 cable.

I attempted some additional troubleshooting including pulling all atached items and adding, and rebooting after item was added. A futile process as when the dock was attached shutting down, and moving to the boot process was very slow. Cold boot was also slow when attached as it attemtpted to connect but failed. Eventually rearranging the displayport and hdmi I managed to get it to at least begin to visibly connect during the initial boot process however soon after entering my encryption password the attached screens would go blank (presumably as GDM took over). Running boltctl list showed the device as being disconnected. Performing a power cycle on the dock would result in an automatic connection.

Seeing as how the device is technically unsupported I decided sadly to return it. A visibly well built unit, I think I ran afoul of an incompatibility with either my hardware, the linux kernel, or the i915 drivers. Some of the errors seen were “failed to reach state TB_PORT_UP. Ignoring port…” “PCIe tunnel activation failed, aborting” a similar “DP tunnel activation failed, aborting” and an assortment of other errors. I have several TB3 docks and accesories which have no problems. I will likely try the plugable hubs next since I have confirmation they work.

Anyway thank you for your time.

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