Computer wakes from sleep at almost exactly the same time every day

An almost exact 3:00 AM wake strongly suggests a wake timer or scheduled maintenance task rather than random activity. Immediately afterward, open an elevated terminal and run powercfg /lastwake, powercfg /waketimers, and powercfg /devicequery wake_armed. These identify the last wake source, active timers, and devices allowed to wake the PC. If a maintenance or update timer appears, open Task Scheduler, locate that task, and inspect its Conditions setting for “Wake the computer to run this task.” Windows has historically scheduled automatic maintenance around 3:00 AM, so also check Security and Maintenance > Automatic Maintenance > Change maintenance settings. Disable wake permission only for the source you confirm; do not turn off all maintenance or updates. If a network adapter or mouse is named, clear “Allow this device to wake the computer” in its Power Management tab. If the commands are inconclusive, generate powercfg /systemsleepdiagnostics and review the recorded transition.