Wake-on-LAN

Wake-on-LAN depends on the network interface being configured to listen for a Magic Packet before the host powers off. Many systems do not keep this enabled persistently — the NIC reverts to a default power-off state after each reboot or power cycle, and a Magic Packet sent to a freshly suspended machine will be silently ignored.

Note

Wake-on-LAN also needs to be enabled in the system’s BIOS or UEFI firmware. This is a one-time hardware setting that Desomnia cannot configure. Consult your motherboard or NIC documentation if unsure.

How to enable

Platform specific tools have to be used to enable Wake-on-LAN for a particular network interface. The following sections explain how to do this for Windows and Linux. Desomnia can take care of this automatically, ensuring the interface is ready every time before the machine suspends. The allowWakeOnLAN attribute on <NetworkMonitor> controls which mode to ensure and is documented in the configuration reference.

Just before issuing a suspend, Desomnia queries the monitored interface to determine whether the required Wake-on-LAN mode is already active. If it is not — and the hardware reports it as supported — Desomnia enables it and records the previous state. After the system resumes, it restores that original value. A machine that had Wake-on-LAN disabled before the suspend will have it disabled again after waking up; Desomnia holds the setting open only for the duration of the sleep.

Attention

If the requested mode is not supported by the hardware at all, a warning is logged and the suspend proceeds normally. The system will still sleep; it simply may not respond to a Magic Packet if the NIC does not support it at the hardware level.

ethtool

OS:

🐧 Linux

Desomnia uses ethtool to read and configure Wake-on-LAN on the interface. The tool must be installed on the system; if it is absent, Desomnia will log a warning at startup and skip the automatic activation.

# Debian/Ubuntu
apt install ethtool

# Fedora/RHEL
dnf install ethtool

You can check the current Wake-on-LAN state of an interface at any time:

ethtool eth0

Settings for eth0:
    ...
    Supports Wake-on: pumbg
    Wake-on: d

The Supports Wake-on line lists all modes the hardware is capable of. Wake-on shows the currently active modes — d means disabled. When Desomnia enables Wake-on-LAN automatically, it changes this to include the configured mode (e.g. g for Magic Packet) just before suspending, then restores it to the previous value after the system resumes.

Note

Changes made by ethtool are not persistent across reboots. This is intentional in Desomnia’s design: the interface starts each boot with Wake-on-LAN in its default state, and Desomnia re-applies the setting every time before sleeping. No additional persistence configuration is required.

PowerShell

OS:

🪟 Windows

On Windows, Wake-on-LAN settings are stored per adapter in the NIC driver and are generally persistent across reboots. However, they can be silently disabled by Windows Update replacing the driver, by power management policy changes, or simply by a non-default factory configuration.

Windows exposes Wake-on-LAN through two adapter properties:

WakeOnMagicPacket

Controls the MagicPacket mode. A Magic Packet addressed to the adapter’s MAC address wakes the system.

WakeOnPattern

Controls pattern-based wake modes: Unicast, Broadcast, Multicast, ARP, and Filter. All of these are enabled or disabled together through a single driver property.

You can inspect and modify them with PowerShell:

# Read current Wake-on-LAN state
Get-NetAdapterPowerManagement -Name "Ethernet" | Format-List WakeOnMagicPacket, WakeOnPattern

WakeOnMagicPacket : Enabled
WakeOnPattern     : Disabled

# Enable Wake on Magic Packet
Set-NetAdapterPowerManagement -Name "Ethernet" -WakeOnMagicPacket Enabled

These properties map to the settings in Device Manager under the adapter’s Advanced properties. Additionally, you have to check the corresponding options under the Power Management tab.

Note

Unlike Linux, changes to Wake-on-LAN settings on Windows persist across reboots. Desomnia can still verify and re-apply the setting before each suspend as a safeguard against silent configuration drift. The original state of these properties will then be restored on shutdown.