ud-3900 ethernet not obtaining a valid ip


Windows 7 32 bit (sigh)
Usb 2.0 port, though the same problem happens on usb3 port
Wireless internet works fine

instead of obtaining a valid ip, the ud-3900 obtains a address.



Hi Steve,

The most common scenario that causes the ethernet port to not obtain a valid IP is related to an upstream device/cable not supporting full-duplex connections, as a full-duplex connection is required by the DisplayLink ethernet port. (Many laptops have a built-in ethernet port that doesn’t require full-duplex, which is why in some cases an onboard ethernet port will get an IP, whereas the dock will not.)

If the dock is connected to a hub rather than a switch, what you’re experiencing would be expected behavior, as hubs do not support full-duplex. Some cables that aren’t fully Cat5 compliant will cause this as well.

Generally the best troubleshooting approach is to connect the ethernet on the dock directly to the router or switch using a different (“known-good”, if possible) Cat5E cable.

Also, as far as a bit of background goes - is this an issue you’re encountering while setting up a new dock, or has the dock been in use for some time with functional ethernet?



Hi Steve,

We’re closing this thread due to a week of inactivity. If you’d like to discuss the issue further please email support@plugable.com and we’ll be happy to help!