I did use WAN (Wide area network) for internet as that is my understanding of what it means. Simply put, I would like to send the magic packet from work to home and wake up my PC at home so I can log into it remotely. This way I don't have to leave it on all day long while I am at work. So it would be sent from 1 subnet to another as you put it. This should be very possible as it is an option on most all of the WOL magic packet sender softwares you download or use. It is also an option under the D-Link 4500 if you look at Advanced > Virtual Server >... You can chose Wake On Lan and it will automaticaly fill the public and local ports 9 for you. I aslo set up a DynDNS so that I can use that to always find my location.
So from outside of my network I should be able to enter:
Host / IP = xxxxxxxx.homedns.org
Mac = xx.xx.xx.xx.xx
Port = 9
and get my PC to kick on. Doesn't work though.
What are you using to transmit the Magic packet?
I've not tried it, but there is this available:
http://www.depicus.com/wake-on-lan/woli.aspx
http://www.ezlan.net/WOL.html
Subnet issues usually refer to dealing with different subnets locally, so that's not your issue. It could be a packet loss issue though, one thing I saw recommended was to repeat the Magic Packet sending at a high rate, with the idea that eventually the whole packet will get thru and trigger the process.
Some other interesting info to consider:
http://www.dslreports.com/faq/6790
I just thought of something else. Could your office or home ISP be blocking traffic over port 9? If so, you can pick a random high-number port, then have it translate in the router from that port, to port 9 internally. Also, you only need UDP, not TCP.
Hope this helps,
Hank