3 display issues

Good Afternoon
I purchased the 3900PDZ docking station and having issues connecting 3 external displays. Would it make any difference if one of the monitors is a different make or do they need to be all the same?. Windows recognises four displays including the Laptop but for some reason one of the displays shows no output am I doing something wrong

Hi Shamir,

Thanks for contacting us, I am sorry this is not working as expected and I am happy to help!

The UD-3900PDZ can support up to three external displays, either all three 1080P (1920x1080) at 60Hz or one 4K UHD (3840x2160) at 30Hz connected to the “HDMI 1” output, and the other two 1080P 60Hz connected to the “HDMI 2” and “HDMI 3” outputs, the displays do not need to be the same manufacturer and model.

I recommend we start by ensuring all displays are set to extended desktop mode, Windows may default to mirroring external displays, but due to a bug in the interface may not show this in the “Display Settings” panel.

  1. Use the Windows keyboard shortcut: [Win]+[P] ( press and hold the Windows Flag Key, then tap the ‘P’ key, release both keys )
  2. From the “Project” menu on the right side of the screen, select the top option “PC Screen Only”
  3. Repeat steps #1 and #2 but select the “Extend” option instead

Please let me know if this helps to enable all three external displays.

If one display is still not working, please let me know which port it is connected to on the docking station. The “HDMI 1” output is controlled by the computer’s internal graphics controller via USB Type-C DisplayPort Alternate Mode, an optional USB Type-C port feature, while “HDMI 2” and “HDMI 3” are controlled by the DisplayLink software on the computer and hardware in the docking station.

Thank you, I look forward to your reply and we can proceed from here.

Plugable Technology

Hi Pat,
Thanks for the quick response I will try when I get back home but in the meantime can you confirm whether or not my Laptop is actually compatible with the 3 display model. I do have the dual monitor display link- with no issues.
My laptop model : ACER SPIN 1 aSp114-31 series
Model No N20W2

Hi Pat, the only port I’m having issue with is port number one HDMI/Alt Mode


Thanks for the system details, it looks like this is the specifications page for this computer ( https://store.acer.com/en-us/spin-1-laptop-sp114-31-c3b6 ).

Acer claims one USB Type-C Gen 2 (10Gbps) port, but does not specify USB Type-C DisplayPort Alternate Mode or USB Power Delivery support, these are optional USB Type-C port features this docking station uses to support the “HDMI 1” connected display, and to power and charge the computer respectively.

I also checked the user manual here ( https://global-download.acer.com/GDFiles/Document/User%20Manual%20W11/User%20Manual%20W11_Acer_2.0_A_A.pdf?acerid=637691718934605221&Step1=&Step2=&Step3=SP114-31&OS=ALL&LC=en&BC=ACER&SC=PA_6 ), from the Left View (PG 13) the USB Type-C port is described as:

Connects to USB devices that adopt
the USB Type-C connector. Support
USB 3.2 Type-C, Gen 2 with transfer
speeds up to 10 Gb/s.

There is no mention of display support on this page, most likely indicating this system does not support USB Type-C DisplayPort Alternate Mode video output.

Similarly on page 54:

On Acer computers USB Type-C ports support up to USB 3.2 (SuperSpeed
USB, 10 Gbps).
Other USB devices with a USB Type-C connector are supported, but transfer
speed may be reduced and certain functions will be disabled (such as
Thunderbolt video support).

Acer may be conflating USB Type-C DisplayPort Alternate Mode video with “Thunderbolt video”, while they achieve similar ends, they are different technologies.

Based on the documentation from Acer I don’t expect this computer will fully support this docking station with three external displays, but we can double-check to ensure the docking station is connected directly to the computer using the original USB Type-C data cable provided with the docking station. USB Type-C “Charging” cables sold separately, or included with other products may not be fully compatible with this docking station and will prevent the “HDMI 1” output from functioning when connected to a compatible host computer.

If the docking station was purchased for this computer within 30 days and within the United States I can help to start the return process for this docking station and recommend an alternative model docking station and graphics adapter to support three external displays with this computer.

When you have a moment, please start a direct email to ‘support@plugable.com’ with the subject line ‘Ticket #414370 - Attention Pat’:

  1. The Amazon Order ID ( available from amazon.com/orders ) for the original purchase of the UD-3900PDZ ( in the form of “###-######-#######” )
  2. The serial number from the bottom of the docking station ( in the form “####A#####” )
  3. Your full, preferred shipping address (in the format below) for generating the return shipping label.

Full Name (Recommended for US addresses and required for international addresses)
Company (if shared)
Street Address
Suite or Unit Number
City State Zip
Phone Number (Only required for shipment outside the US, but can be helpful for domestic carriers as well)

Or if the docking station is being shared between multiple computers I can help to recommend how to connect the three displays to both the docking station and one directly to this computer so that it can be used with three external displays.

Thank you, and I am sorry for this inconvenience.

Plugable Technology

Hi Pat,
This is what I thought I didn’t think this model laptop supported 3 displays from the display link rather than returning can you tell me how I can I use three screens with my laptop and also maybe suggest a model of laptop mid price range which would support three screens. The ACER is a work computer and I could put it to them that I need a different computer as usding three external displays are a lot more productive in my work line on a daily basis

Hi Shamir,

Thanks for replying back, I can provide some options for three external displays:

  1. The computer can have the third display connected directly to the built-in HDMI output, with displays #2 and #3 connected to the docking station’s “HDMI 2” and “HDMI 3” output ports.
  2. A USB 3.0 to HDMI adapter can be connected to the docking station to enable the third display, for example our UGA-2KHDMI ( https://plugable.com/products/uga-2khdmi ) can support a third HDMI display up to 1080P (1920x1080) resolution using the same DisplayLink technology as the docking station.

For alternative docking stations, our UD-3900C ( https://plugable.com/products/ud-3900c ) or UD-3900H (https://plugable.com/products/ud-3900h ) may be good options, these will need the UGA-2KHDMI USB to HDMI adapter from above to support three external displays.

  • The UD-3900C is a vertical docking station with two HDMI outputs capable of supporting two 1080P displays using the same DisplayLink technology as the UD-3900PDZ docking station. This docking station does not provide power to the notebook ( you can check to see if the notebook is charging with the UD-3900PDZ connected, I suspect it is not based on the specifications ).
  • The UD-3900H is a horizontal docking station like the UD-3900PDZ, with one HDMI and one DVI output, it includes a DVI to HDMI adapter for the second 1080P display. Like the UD-3900C this docking station does not power the host computer.

Both of these docking stations provide two USB 3.0 ports, and four USB 2.0 ports for connecting USB devices, Ethernet, and 3.5mm headphone and microphone ports. The UGA-2KHDMI can be connected to a USB 3.0 port for best display performance.

Please let me know if you have any additional questions, or if there is anything else I can do to help.

Plugable Technology

Hi Pat,
I think I will try the option 1 and see how I get on and if it doesn’t work I’ll try option 2 with the adapter and is this available to buy on amazon

Hi Shamir,

Thanks for the update, I look forward to hearing back after you have had a chance to try this setup.

Yes, the USB to HDMI adapter is available on Amazon, you can get to the store page by clicking on the link on our product page linked above.

Thank you,

Plugable Technology

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