To properly support Wake on LAN a computer must meet the following requirements:
- The network card must be WOL capable.
- The power supply for the computer must supply appropriate current to the network card while the computer is in a reduced power state.
- The drivers for the network card must support WOL.
- The system must be configured in both the bios and operating system to allow the workstation to be powered on from a sleep state by the network card.
Additionally the local area network must be configured to allow the Wake on LAN packets to propagate through the network. If UDP broadcasts are blocked, ports are being blocked, or machines are segregated into different network segments based on their state, then Wake on LAN may not function properly in your environment.
As each hardware vendor's implementation of Wake on LAN will be different there is no common setting that can be used to identify the settings for Wake on LAN. In general the settings will be found in the "Power Management" or "Remote Wakeup" section of the BIOS. Settings within Windows are managed in the device manager properties page for each network card.
If Wake on LAN packets seem to fail over time then problem could be that workstations are still referenced in the ARP cache present on most routers and switches for a short period of time allowing a directed packet to reach the appropriate endpoint even though the endpoint is offline. Generally this type of behaviour will result in the WOL request failing after the workstation is off for 10-20 min. To resolve this the network will need to be configured either to use a Wake on LAN relay in Core, or to allow for network broadcasts to be passed through the network.