Just a quick post but I’m sure I’m not the only person who will hit this. I noticed that in Windows 8 Consumer Preview I couldn’t get Wake on LAN (WOL) to work on hardware that had been fine for WOL before. A bit of digging around lead me to disabling “fast boot” or fast startup in order to get it to work. Basically fast startup is sort of like a hibernated start, key files are loaded from a disk image to memory to allow faster boot, but it seems to be incompatible with WOL.
In Windows 8 CP there was a tick box in the Control Panel to disable it
Update 24/11/2012: Thanks to Gizmoe in the comments, this option is in the RTM version of Windows 8, under Control Panel, Power Options “Change what the power buttons do”, then at the bottom “shutdown settings”. You will need to click the button to get to the administrator UAC level.
In RTM the option has gone, but you can still disable it via a registry key
Step 1: Open the Windows Registry editor
Step 2:open key HKEY_LOCAL_MACHINE \ SYSTEM \ ControlSet001 \ Control \ Session Manager \ Power
Step 3: Locate the key HiberbootEnabled and double-click on it
Step 4: Set the value of the key to 0 to deactivate fast boot
Step 5: To restore the setting at a later time, change it back to 1.
Step 6: next open key HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Control \ Session Manager \ Power
Step 7: Locate HiberbootEnabled there and double-click the entry and Change the value of the key to 0 to deactivate Fast Boot.
Source Credit: Tech2Fun
After setting this Wake on LAN was once again working nicely in Windows 8 RTM.