关闭允许离开模式策略，以使睡眠模式有效

I have finally solved an annoying problem with my Windows 10 setup which was sortof hard to Google, so I am sharing. For quite some time, the computer had refused to go to sleep when it was not running on battery. Instead of going to sleep when instructed to, it would simply turn off the screen and mute the volume while continuing to actually not sleep. Moving the mouse a tiny bit would swiftly end the charade. In a recent fit of rage I decided to inspect the event log, and behold, there were some Kernel Power events that said:

The system is entering Away Mode.

Which is entirely not what I wanted when I told it to go to sleep. However, there was no option anywhere in the power settings to be found that turned off this "Away Mode". Well, the option actually does exist, but for some reason it is not visible unless you set the Attributes value to 2 in the following, easily memorable registry key:

HKLM\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\238C9FA8-0AAD-41ED-83F4-97BE242C8F20\25DFA149-5DD1-4736-B5AB-E8A37B5B8187

Armed with this registry tweak, you can go back to the "advanced" power settings, aka:

rundll32 shell32.dll,Control_RunDLL PowerCfg.cpl @0,/editplan:

Navigate to Sleep and there should be an option that says Allow Away Mode Policy or something similar. And that policy should be set to no, not even when plugged in, never, just sleep, for crying out loud, why does this even exist.