U3900 ethernet connection recognized by computer but cannot connect.

Installed U3900. All works well except ethernet (en) connection. Displaylink en appears on list of available nets but is not connected. Cable is good. I plugged cable directly into my laptop with doc unplugged and en was available. I went thru advance settings and the defaults were good. My laptop is a Toshiba Satellite P745-S4320. It basically acts as tho no cable attached.

Hi John,

Thanks for posting. I’m sorry the Ethernet port isn’t working on your dock. I’d be happy to help.

Is sounds like you have already checked the obvious (the cable itself, etc.). Do any of the lights by the Ethernet port on the dock light up when you try to connect?

By any chance are you connecting to an Ethernet hub as opposed to a switch?

The Ethernet controller in the docking station requires a full duplex connection. Half duplex connections are not supported. Often, the issue is caused by older Ethernet hubs and/or cabling that do not support full duplex connections.

If you are in fact connecting to a switch, I would like to get some more details about your setup. We have developed a utility called PlugDebug which gathers some information about your system. It is available from this link:


At your convenience if you would follow the instructions on that page for your operating system and send an email to support@plugable.com with ‘Ticket 84004’ in the subject line with the .ZIP file that the application creates?

** Please to make sure to have the Ethernet cable plugged into the dock (even if it isn’t working) when you run the program **

Once we have the file we can determine the next steps.

Thank you,

Plugable Technologies