Windows 11 has a feature called Fast Startup which is enabled on many computers by default.
When Fast Startup is enabled, selecting Shut down does not perform a completely fresh shutdown. Windows saves part of the system state so it can start more quickly next time.
This can cause confusion when troubleshooting. For example, Task Manager may show that a computer has been running for days or weeks even though the user regularly shuts it down.
A Restart performs a full restart, but disabling Fast Startup makes a normal shutdown behave more like a traditional shutdown.
Disable Fast Startup
Open the Control Panel and go to:
Hardware and Sound > Power Options
Click:
Choose what the power buttons do
Click:
Change settings that are currently unavailable
Under Shutdown settings, untick:
Turn on fast startup (recommended)
Click:
Save changes
Windows will now perform a full shutdown when you select Shut down.
Why Disable Fast Startup?
Fast Startup can make troubleshooting more difficult because shutting the computer down does not completely restart the Windows kernel.
This can allow some problems to persist after a shutdown and can also result in Task Manager showing a much longer system uptime than expected.
On modern computers with SSD storage, the difference in startup time is usually small, so disabling Fast Startup is often preferable on business computers.