Plugable UD-MSTHDC docking station not extending to third monitor


I bought this docking station because of the 2 display port compatibility it has and it was listed as compatible with ChromeOS. I’m using two external monitors with Display port cables(both are the same - HP Compaq LA2206x) that I was hoping would work with my Acer Chromebook CB311-11H-K04N. The monitors don’t have HDMI ports. ChromeOS is the latest version 112.0.5615.134.

The two monitors work, but my chromebook is only detecting one monitor as a device. I extended to the detected device, which is the screen monitor. The problem is that the third monitor is only mirroring the second monitor. I want to extend to all. How can I make this work? Please help.


Thank you for contacting Plugable! I am sorry to hear that your UD-MSTHDC docking station is not functioning as expected, and would be happy to provide additional support.

For my reference, does the same problem occur if the dock is connected to a laptop with an Intel CPU (if available)?

I ask because it looks like your Chromebook does not have an Intel 11th gen or newer CPU, which could be the source of the issue you are seeing, as MST docks (such as the UD-MSTHDC) depend on their CPU for supporting external displays.

Additionally, could you also kindly provide a screenshot of your display settings screen? I ask because you should be able to set both external displays to “Extend” to prevent them from mirroring each other.

Moving forward, we’ll also want to perform a full power-cycle of the unit to reset its internal hub chipset one more time. We’ve seen that this can often restore the dock back to a working state when one or more of its functions are not quite working. To do this, please follow these steps:

  1. Disconnect all USB peripherals and displays connected to the dock
  2. Disconnect docking station from host machine, then disconnect the power adapter from power
  3. Leave unplugged for 1 minute for power to dissipate
  4. Connect docking station initially into power only
  5. Connect docking station to host machine, then connect USB peripherals and the displays, then test for functionality

If these steps help, great! If not, please let me know so I can take a different troubleshooting approach.

Thanks for your patience while we work to help!

Plugable Technologies

I’ve tried the reset and it’s still only picking up one monitor in my chromebook devices and mirroring onto the third display.


Thank you for letting me know!

Based on your description of the issue, it seems like your ChromeOS host is not fully compatible with your UD-MSTHDC dock. At this point, I would recommend returning this unit under Amazon’s 30-day hassle free return window (or other distributor).

Sorry I could not be more helpful, but please feel free to reach out if you have any follow-up questions or concerns.

Thank you!

Plugable Technologies

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