U2722DE, constant USB connect/disconnect sound on Windows

I recently had the following frustrating problem. I managed to solve it myself, so I'm posting my experience here so someone can hopefully benefit from it in the future by finding this thread through search. 

For some reason, my laptop (ASUS Zenbook with Windows 11) started making the USB device connection sound, immediately followed by the USB device disconnection sound, every 30 seconds. This was happening constantly. Reviewing Windows's Event Viewer > Windows Logs > System showed that a device was constantly being plugged in and unplugged, causing the issue. The source was listed as "nhi", which didn't narrow down the device or driver causing this. 

I researched a lot online, most advice pointed to disabling Windows' USB Selective Suspend setting. The problem didn't go away even after doing that (it's difficult to do on Windows 11 - you have to use a terminal command, as the system-wide USB Selective Suspend setting was removed from Windows's Power Options). 

After pulling my hair out of frustration, I then started disconnecting devices from my laptop to narrow down the issue. It turned out the issue was with my Dell U2722DE monitor. Having the monitor plugged in via USB-C, even with no other peripherals connected via the monitor's ports, was causing the constant connect/disconnect sound.

I was already on the latest firmware for the monitor, version M3T107, having updated the firmware recently (I have a suspicion the firmware update might've caused this in the first place). There's no way to rollback the firmware to the factory version, so I tried reinstalling the M3T107 firmware, strictly following the instructions this time. This didn't make a difference - the issue was still present.

Finally I tried the "Factory Reset" option from the monitor's on-screen menu.



After the Factory Reset, the problem went away! Fingers crossed it doesn't return. Hope this helps others as well, as I didn't find this online anywhere!