TBT3-UDV at times won't connect to the computer

About once in a couple of months TBT3-UDV goes into a weird state when the blue light wouldn’t come on when the attached computer is powered on. The green light is on, so it’s powered up Ok.

The issue is intermittent - I would work one day normally, with a 4K display attached via TBT3-UDV, then power it down for some time - all cables are attached and not disturbed in any way, then power on the computer and the blue light on TBT3-UDV doesn’t come on and the computer doesn’t see the dock. The green light on TBT3-UDV is on when this is happening.

I am attaching the computer via the non-powered TBT3-UDV’s port because of the problems described in my other thread with the powered port:

LG 4K monitor reports that supplied cables should be used - Thunderbolt 3 / TBT3-UDV - Plugable Support

Computer Thunderbolt ports are working fine on their own.

I cannot test the other TBT3-UDV port because of the problems described in the thread mentioned above - comes back with an unrecognized USB device message, which it does half the time even when TBT3-UDV is working.

A couple of times in the past powering down/up TBT3-UDV seemed to have helped. Today, however, it didn’t work and I spent some time rebooting the computer and switching cables, etc - nothing worked.

I left it alone for about an hour and when I came back and powered up the computer, the blue light in TBT3-UDV came on. Same setup - nothing was changed since when it wasn’t working.

It is as if there’s something dangling around a threshold in the TBT3-UDV, like a dying capacitor.

I bought TBT3-UDV in October last year, so I have a few more months and it likely will happen again at least once. Can you please advise what tests do you want me to run to prove/disprove whether it’s a hardware fault in the device or not? Thanks

Hello Andre,

Thank you for contacting Plugable support! Sorry to hear about this issue. I’d be more than happy to assist you.

We have a troubleshooting tool that helps us find out what is going on in situations like this. Please plug the dock into your computer, then go to this page and follow the instructions there:


From the issues you are describing we may ultimately need to replace the dock under warranty, though I’d like to try and rule out any software issues first that could be causing trouble. If nothing stands out, I’ll ask for some additional information so we can do a warranty replacement. It would probably be best to get a set of diagnostics with the dock in a bad state if possible.

Please don’t hesitate to let us know of other questions.

Thanks again for contacting Plugable support and best wishes!

Joshua Henry

Senior Engineer
Plugable Technologies

http://plugable.com | http://performance.plugable.com/

Thanks, Joshua

It happened again this morning and this time I tried to connect the monitor via the TB-to-HDMI dongle that came with the laptop and the connection didn’t work, so it could be something with the TB ports on this laptop. Reboot didn’t help, but when I powered down the laptop and started it again, everything was working, including all devices plugged via TBT3-UDV.

Please, keep this thread open for now, if you don’t mind, and if it happens again I will do some more troubleshooting with other USB3/TB devices. I was under the impression that TB ports were working when I originally posted and now I’m not sure that was correct and want to double-check.

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