Hopefully this will help people smarter than me to solve the problem.
I'm running a network with a 2Wire 2701HGV-E Gateway. (I've enabled UDP port forwarding) I do not have an airport express or extreme. My network is primarily wireless, however my appletv is connected to the router by ethernet, and the computer I have been trying to wake is connected via wall-plug in another room (ie wired internet with dlink homeplugs intervening). The computer is a 2008 macbook with wake on network enabled. (it predates wake on wireless)
The macbook has its wifi disabled. It's running os x 10.6.8.
My appletv has never been able to wake it (or any of my 3 other macbook pros, including a 2012 macbook pro running mountain lion) via ssh or bonjour print, or even itunes. When I put any of the computers to sleep its library vanishes immediately from the appletv "computers" list. The same thing happens with my apple remote app on my iphone.
Bonjour browser shows that whenever any of my computers sleeps (with lid open) all the services they are offering, eg airprint, itunes vanish. There's no lag period, they just drop out. This leads me to conclude that they are not registering their services with the ATV3 when they go to sleep.
I am able to wake up the macbook using VNCLite on my iphone and my MBPs, illustrating that the WOL packet is being delivered to the router, then thru the wallplugs to the macbook just fine. All its bonjour services reappear immediately. After reading the many, many websites which I'm sure you've all been to by now, I concluded that the problem was a lost cause and the only solution would be an airport express.
Here's where it gets interesting.
I decided to install shairplay on the macbook, which was a story in pain and frustration thanks to the extremely poor online guides (what's with mac developers writing only for other mac developers and not the end users??)
and the hundred or so different versions out there, and also because i'm a PC user and compiling on os x has been a learning experience. Anyway I finally got it working right, after following this guide :
having it not work, installing... a LOT of other dependencies by hand (including avahi), and finally uninstalling avahi.
And then my macbook miraculously woke when I absent mindedly played some music on it from my iphone apple remote app while it was sleeping. The phone tries to open the library (nothing shows on the list initially) as it was left open, and in trying to open the library it somehow wakes the macbook.
Assuming I had somehow repaired the link to the sleep server and that the problem had been on the client side, I tried to replicate this with the ATV 3... But the ATV3 does not see the library at all when the computer is asleep!
Once the macbook goes to sleep the library drops off the ATV3 list; there's no way to try to reopen it from the apple tv, unlike my iphone.