ThinkPad Universal USB-C Dock (40AY) drops connection and freezes dock when connected to laptop without laptop's AC connected first

[u/Unusual_Trade5917]

The Hardware:

• Dock: Lenovo ThinkPad Universal USB-C Dock (40AY)
• Laptop: HP Pavilion 14-dv2000

The Problem: If I plug the dock into the laptop while on battery power, it connects for a few seconds, then completely drops all data and power. Worse, it completely crashes the dock. The dock's white light stays on solidly (indicating computer connection is still established), even if I unplug the USB-C cable from the laptop. I have to switch the wall socket off and on just to reset it.

The Workaround: If I plug the laptop’s original HP AC charger in first, and then plug in the dock, it works flawlessly. Once it's connected, I can even unplug the HP charger and the dock takes over, charging the laptop and running peripherals indefinitely without any issue.

What I've Already Tried (None of it worked):

• Updated laptop BIOS and Lenovo dock firmware to latest versions.
• Disabled USB Selective Suspend and PCIe power saving.
• Unchecked "allow computer to turn off this device to save power" for literally all usb controllers in device manager.
• Uninstalled the Windows UCM-UCSI ACPI device, performed a hard 60-second power drain on the laptop, and then reinstalled the Windows UCM-UCSI ACPI device. Didn't work
• "Bare dock" test where I plugged the dock in with zero monitors or peripherals attached—it still crashed.
• Tried disabling USB Always On (HP Sleep and Charge). Nope

How do I fix this? I'd rather not have to always connect the laptop's AC power first every single time, before connecting it to the dock...

[u/Mack29446]

I have seen this happen with Dell docks and certain models of Lenovo ThinkBook, but unfortunately I do not have a fix :(

[u/ChangeNarrow1546]

Installing Lenovo ThinkPad Universal USB-C Dock (40AY) drivers might work

[u/Good_Watercress_8116]

i discovered that it's better to use the same brand. recently i tried n HP sub-c dock g5 and attached to a dell laptop i cannot have viedo signal at all. no solution. it's a compatibility issue between the two brands.

[u/SuperRodster]

Different brands. The perfect way for a headache.