Is it only the NS that sends the WOL broadcast or do the site servers send it too?
it's task server based, so the NS and the task services on the site servers are responsible for WOL.
Nice article regarding WOL: http://www.symantec.com/docs/HOWTO60817
Any computer with the Symantec Management Agent installed can send a WOL broadcast. Task must be working properly in the environment for this to function, since that's how the NS sends the notice to the proxy client (via site servers running task service). The proxy client then broadcasts to the computer you targeted for WOL.
Does this help?
Mike Clemson, Senior Systems Engineer, ASC
Intuitive Technology Group -- Symantec Platinum Partner