Even though PlexConnect can be modified to send the magic packet, this would not solve cases where you want to wake from remote requests, or from other Plex clients. I’ve never tried this myself, but from what I’ve seen from others, they opted to use router’s facilities to wake PMS.
Furthermore, I’m not sure that PMS allows your server to hibernate, in Linux platforms this is almost impossible, but maybe it’s possible in Windows. Take a look at this post, maybe it will give you ideas on how to implement what you want.
Be aware that, although sleeping has the benefits of lower electricity bill and less constant noise, it will shorten HDD life.
