1000MB on UD-3900


I have a PLUGABLE UD-3900 and when I plug the NIC into a Gig network connection it keeps going from connected to disconnected. Works fine on same switch when I make the port 10/100. Even “Auto” doesn’t work. Any thoughts?


Hi Joe,

Thanks for posting! I’m sorry the connection isn’t working properly. I’d be happy to help!

The first thing to check is the Ethernet cable itself. As a gigabit connection uses all eight conductors in a standard Ethernet cable (as opposed to four in a 100Mb connection) a cable with faults can sometimes work well at one speed and not so well at another. Do you have another cable you can swap in as a test to see if the behavior is any different?

Thank you,

Plugable Technologies


I do, I have tried 3 cables, all are brand new Cat6 cables. The same cables all work on other gear, some Gig some 10/100.


Hi Joe,

Thanks for testing with the additional cables! The next step would be to try cleaning the current DisplayLink drivers from your system and re-installing the latest we recommend. Please follow these steps:

  1. Disconnect the dock from the computer and please remove the power cable from the dock so it turns off completely. Please keep it disconnected until the last step.

  2. Uninstall the DisplayLink Core software from the Control Panel -> Programs and Features. Don’t worry if this fails, just move onto the next step

  3. Download, extract and run the DisplayLink cleaner tool, found here:

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

  5. Now download and run the 7.7 M4 DisplayLink software, found here:

  6. Reboot, even if not prompted to

  7. Once you’re back in Windows, reattach the power cable to the dock first. Once the dock is powered on, reconnect it to your PC which will trigger the final portion of the installation

Please let us know if that helps. If the issue persists, please run our diagnostic tool PlugDebug --> http://plugable.com/support/plugdebug and send the output to support@plugable.com with ‘Ticket 101107’ in the subject line so we can match everything up and support you directly as we may need to send you a replacement dock. If you could also include your Amazon Order ID number for the dock that would be great.

Thank you,