On devices with Modern Standby, if you are plugged in and you simply close the lid (without explicitly pressing "Sleep"), some network adapters are configured to stay in D0 (fully on) state. You can check this:
If you close your laptop lid, it usually triggers sleep mode immediately. To change this:
Windows Vista/7 had a true "Away Mode" that kept the network alive while appearing off. In Windows 11, this is deprecated but can be partially emulated via Group Policy or registry hacks that set AwayModeEnabled=1 under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power . This often leads to instability, fan noise, and unexpected wake-ups. Not recommended for average users.
Use a download manager that supports "prevent system sleep while active." Examples: