Microsoft has introduced Connected Sleep in Windows 8.1, where the notebook (or PC) does not turn off entirely but instead enters an extreme power-saving mode. At the same time, some essential functions (such as internet connection) continue to work. In Windows 10, this has been replaced by Modern Standby, but not all legacy devices support this feature. Luckily, it’s not too hard to check if your machine is OK with the feature!
Start a command prompt (Win key, then type “cmd”). Type “powercfg -a” and check the list of power-saving features supported by the machine. If the device supports the Modern Standby feature, The following sleep states are available on this system section will include the entry Standby (S0 Low Power Idle). If only the Standby (S3) entry is shown, unfortunately, the PC in question does not support Modern Standby.