Wake-on-LAN is a standard that allows a computer to be turned on or woken up by a network message called "Magic Packet".
Amahi supports waking up machines devices that have a dynamic or statis DHCP leases in your network, under Setup > Networking.
These machines devices some times come with WOL enable. In many PCs, they need to be setup properly by enabling WakeOnLan in their BIOS of the machine. This setting has quite a few names in BIOS's out there. Here's a couple of them <small>(find the one you need in the user manual of your motherboard/system)</small>:
* MAC Resume From S3/S4
* MACPME Power Up Control