HDMI 3 and 4 not detecting monitors on plugable ud-3900c4 docking station

Hi Andy,

Thanks for reaching out to Plugable support! I’d be happy to help with that.

Looking at the support information for this particular computer, it looks like the USB-C port does not support the required Alt Mode or MST that is necessary for HDMI ports 3 and 4 to function for this doc. It looks like this laptop also does not support laptop charging through the USB-C port.

In spite of this incompatibility with the laptop, you should be able to achieve connection to HDMI ports one and two, along with all other functionality except the additional 2 display connections and laptop charging.

Here are a few lengths that explain compatibility requirements for this docking station more more thoroughly.

How do I know if my computer supports Multi-Stream Transport (MST)?

What is the difference between the DisplayLink vs Alt Mode MST ports?

Thank you for giving us the chance to help.

Richard A
Plugable Technologies
https://plugable.com/support