Multiple TBT3-UDC3 Docks Blinking Monitors and Disconnecting


We purchased 8 of these docks total (5x Walmart Online, 3x Amazon), we have had issues on most of them with blinking monitors and disconnecting peripherals & ethernet on varying monitors.

We have been using the docks in conjunction with the Dell Precision 3560 laptop.

Note All laptops have Windows 10 - 20H2, latest Chipset/MOBO/GPU Drivers, latest BIOS.

Tried plugging the dock directly into the wall outlet, as well as power surge strip.

Tried Airplane Mode, lowered the Wi-Fi output power, turned Wi-Fi completely off, unplugged Ethernet cable (we have Cisco 8841 VoIP Phones with data passthrough for network/internet connectivity).

Tried different cable from Dock > Laptop.

To give you an idea here is a few examples of the setups we have for different users:

Setup 1
TBT3-UDC3 Dock via cable that came with the dock
Dell Precision 3560 Laptop
2x Dell U2415 Monitors

Result: This setup was by far the worst, it immediately flashed both monitors and disconnected the peripherals etc, no amount of power cycling both dock and laptop or the above mentioned fixes worked. We ended up using a TBT3-UDV Dock with HDMI to USB-C adapter and it worked fine.

Setup 2
TBT3-UDC3 Dock via cable that came with the dock
Dell Precision 3560 Laptop
1x Dell U2415B
1x Dell U2417H

Result: Intermittent flashing of both monitors, a few power cycles of the dock and rebooting the laptop would rectify this for the day usually, every time the user came back into work and re-docked the laptop, the flashing would begin again until a few power cycles. We ended up using a TBT3-UDV Dock with HDMI to USB-C adapter and it worked fine.

Setup 3
TBT3-UDC3 Dock via cable that came with the dock
Dell Precision 3560 Laptop
2x U2417H

Result: Same as setup 2, but so far the blinking has stopped after about a week so we did not switch it out with a TBT3-UDV Dock.

I’m wondering where to go from here, did we get a lemon batch from 2 different retailers? The laptops work fine with the TBT3-UDV Dock, and with other brand docks, so I am not convinced the laptops have something wrong with them.

Is there some compatibility issue with the TBT3-UDC3 Dock and the Dell Precision 3560 perhaps?

Please let me know if you need more information or any other potential fixes I can try, at this point I don’t trust this dock with the laptop at all and may need to return them unless you can hopefully help.


Hi Miles,

Thanks for posting!

I appreciate the detailed write-up of the problems you’re seeing. What you report is definitely concerning and I agree with you it is unlikely the laptops themselves have a problem. It would be incredibly rare to receive this many defective units, so we’ll want to explore further here to see if this may be some kind of odd interop issue with this host.

Firstly, as a temporary test, what if you connect the original power adapter to the Dell laptop? Then, with the dock connected, are the same issues present? I understand that this is not an ideal workaround as the dock should be charging the laptop itself, but this helps us understand if this could be related to the Power Delivery negotiation failing in some way.

Next, if possible, does your environment have another different USB-C, Thunderbolt 3, or Thunderbolt 4 laptop to connect to the dock? It would be useful to see if another host experiences the same issues.

From there, I would like to clarify a detail you mentioned. You stated that you have had issues on “most” of the TBT3-UDC3 docking stations. Does that mean that there exists a few identical configurations that are working 100% as expected with the dock?

Lastly, I’d like to request some logs from one of the Dell systems to see if we might be able to see any conflicts that would explain this. Please simply keep the dock connected to the Dell laptop, then navigate to our PlugDebug tool and follow the instructions there.

Please send the ZIP file created to us directly at, and you may include “Ticket #346295” in the subject line so that we can prioritize the case and match it up to this post.

Thanks for giving us a chance to help!


Hi Mitchell,

Thank you for your quick reply. I will try the original Dell power adapter connected for power delivery, and then try the dock and see if that fixes it.

I’ll have to look around for another device to with USB-C , TB3 or TB4 and try that with the dock.

Sorry for not being clear on all the configurations, yes we actually do have some configurations that are working 100% expected with the dock. We have 2 setups using a single 40" TCL 4K TV in HDMI 2.0 mode working great, we also have another 2 setups with 2x Dell 27" monitors (forgot the exact model sorry) working fine - what was odd with these 2 setups with the dual Dell 27" was that they seemed to just work after a while… After a few days of troubleshooting these 2 setups, they work great now. The problem was more so when they would ‘re-dock’ in the morning, it would flash, they would reboot/power cycle dock and it would be fine for the rest of the day. Though this issue doesn’t happen anymore (possibly some driver installed via Windows update, not sure).

I will try running the debug tool on the Setup 1 system when I can and send that to you, might take a day or so just FYI.


Great! Please do keep me posted when you can. We’ll move forward from there.

Looking forward to hearing back from you.


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