VGA monitor on HDMI port not working

DVI monitor on DVI port is OK. A second DVI monitor attached to an HP USB Display adapter also works fine. (Have tested both with and without this adapter plugged into the UD-3900.

I am using an active HDMI to VGA cable, which worked fine to connect the VGA monitor to the HDMI on the laptop while I was waiting for the dock to arrive.

Display properties shows all 3 monitors plus the laptop display, however the VGA monitor reports no signal detected. I tried to move the HDMI to VGA to the laptop’s HDMI, but this does not work with dock attached. Removing the dock, the laptop HDMI works again, using the same HDMI to VGA cable.

Suggestions, please?

Hi Bill,

Thank you for posting! I am sorry things are not working as expected with your UD-3900 docking station and I would be happy to help.

You mention that you are using an, “active HDMI to VGA cable”. Can you confirm if the cable you are using is a Plugable brand HDMI to VGA video cable? →

You also mention that, “Display properties shows all 3 monitors plus the laptop display, however the VGA monitor reports no signal detected.”

While everything is connected, may I ask you to double-check within the Display Settings application (available via right-clicking on an empty space of your desktop), under the ‘Multiple displays’ section, that each monitor is set as an Extension of your desktop? (you will have to click on each monitor number at the top of the window to check the setting for each one).

In other words, we don’t want Windows marking any of them as ‘Disconnected’. I also made a short video showing steps should you need it →

Thank you for giving us the chance to help!

Plugable Technologies

No, it is not a plugable product. I am reluctant to go to additional expense without some assurance that mine is a supported configuration and the issue is likely to be resolved by going to additional cost.

I have done as you suggested and all monitors in turn show “Extend desktop to this display”.

Additional information: I have the VGA monitor at the extreme left of my monitor arrangement illustrated by display properties. My arrangement is 1, 2, 3, 4 left to right, with 2 as my main display. If I scroll my mouse pointer left of #2, rather than dead-ending on the side of display 2, the pointer disappears as though monitor #1 is functioniing. If I shift the display order to 2,1, 3, 4 the mouse scrolls right from 2 (main display), disappears then reappears again on 3 and 4 as though #1 were a fully functioning monitor. So Windows thinks the VGA monitor is there and has extended the desktop across it, I just can’t see the image.

Hi Bill,

Thank you for getting back with the update. I appreciate the additional detail you provided, and the confirmation that all of the detected displays are configured in ‘Extend’ mode (and none are ‘Disconnected’).

You mention that the HDMI to VGA video cable you are using is not a Plugable product. In our experience, the compatibility of 3rd-party HDMI to VGA adapters or video cables used in conjunction with our UD-3900 dock varied widely, and their performance could not be guaranteed.

Since we cannot guarantee the compatibility or performance of 3rd-party products, we starting offering our own HDMI to VGA video cable → The Plugable HDMI to VGA video cable is compatible with the UD-3900.

Understood of course your hesitancy to purchase an alternative HDMI to VGA solution unless a different result can be guaranteed. Everything in aggregate would appear to indicate the 3rd-party HDMI to VGA cable is the source of the problem, however there is always the possibility that there could be other contributing factors. As a result, we could not guarantee a different outcome with the Plugable HDMI to VGA cable.

That said, given your description our next step is to simplify your setup to a certain degree and perform a ‘clean’ installation of the latest version we recommend of the dock’s required DisplayLink driver to help ensure it is in a good state and not contributing to the current behavior. To do so, please follow these steps:

  1. Please disconnect the dock from the system and please disconnect the power cable from the dock so it turns off completely (this is important so the unit resets). Please also temporarily disconnect the HP USB display adapter you mention using from the dock. Please keep everything disconnected until prompted.

  2. Uninstall any and all software with ‘DisplayLink’ in the title that is present from within the Control Panel → Programs and Features. Don’t worry if these entries are not present or if the process does not work, please just move onto the next step.

  3. Download and run the DisplayLink Installation Cleaner utility, found here → and ensure it displays “Cleaning Complete” when done (video walk-through if you need it →

  4. Once the Cleaner has been run, reboot the system (even if not prompted to).

  5. Now download and install the 9.0 M1 DisplayLink software driver, found here →

  6. Disconnect the HDMI to VGA video cable from the dock. Leave only the display connected to the dock’s DVI video output.

  7. Reconnect the power cable to the dock. Once the dock is powered on (a blue light will be present on the front), reconnect it to your system. If the device is not detected, please reboot the system.

  8. Test the behavior with the single DVI display connected to the dock.

  9. Reconnect the HDMI to VGA video cable to dock and test the behavior of the two displays (one connected via DVI, the other connected via the HDMI to VGA cable).

  10. Reconnect the HP USB display adapter to the dock to add the third DVI display, and test the behavior.

Apologies for the long post…please just let us know the results of testing as described above as time allows and we will determine the next steps from there.

Thank you,


Hi -
I went through the steps described above and now all monitors are working properly, even with the 3rd party HDMI to VGA cable.

Thank you for your assistance.

Hi Bill,

Thank you for getting back with the update, and you are of course most welcome for the help. I am glad to hear that everything is now working as expected.

Please let us know if you need any help in the future, and please have a good day!


I went thru these steps and still can not connect my monitors. I have a blank monitor and I have a monitor with vertical lines. I have submitted a help tick, but haven’t heard back.

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