Not able to send WOL Magic Packets from W7HP64bit.

Hello!
Wake-on-LAN has apparently been a major headache for many, and I've tried to search all sorts of forums for similar problem as mine.
Usually the problem is that one can't wake computer X either inside or outside LAN. Well this isn't my problem, since my computer X (old Acer 1692WLMi laptop with Windows 8 Pro as mediabox in livingroom) DOES wake up. I can wake it using iPad/iPhone (Remoter VNC app) inside my LAN.

The problem is, that I can't wake this computer X from my primary home computer Y (Gigabyte GA-EP35-DS4 MOBO, Integrated Realtek gigabit network adapter, Windows 7 Home Premium 64bit). This USED TO WORK for a long time, and then just suddenly Y stopped waking. I normally used mc-wol to wake X from Y with simple batch command line file. I've tried mc-wol and cmdwol, and I'd like to do this with a simple DOS command.

I've tried to disable firewall and to downgrade LAN adapter driver to the one that Gigabyte offers on their website for my MOBO, with no result.

I thought this must be somehow tied to my LAN adapter. But I found out a strange thing: I'm ALSO able to wake up the computer X with computer Y, if I run the same command line tool (cmdwol) with the same parameters from Windows 8 Pro 64 bit, that is installed a on virtual machine (VirtualBox) on Y. This virtual machine has a bridged adapter to my "real" LAN adapter and has it's own IP inside my LAN.

So, it seems, my computer Y is swallowing all the magic packets, but only if they're sent from the primary Windows 7 installation.

Any ideas? And please don't suggest Win 7 re-install, I've got far too many programs installed on this machine to do it for a minor glitch like this.