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BugZero found this defect 179 days ago.
Dell P3424WE monitor may lose connection to USB devices connected to its downstream USB ports. The monitor may also lose a Wired Ethernet connection simultaneously. The issue occurs when pressing the CTRL key repeatedly on a keyboard connected to the monitor. A USB disconnect sound may be heard from the computer. The same issue can happen when pressing and holding the left and right mouse button for 3 to 6 seconds on a mouse connected to monitor. Affected Monitor: Dell P3424WE Monitor
This is due to the default hotkey combination in the P3424WE monitor's internal USB controller which is not documented.
Updating to Dell_P3424WE_FWUpdate_M2B104_Windows version M2B104 or later on the computer resolves the issue. To download and install the firmware, reference How to Download and Install Dell Drivers.