Question on WAKE On LAN and Relay WAKE On LAN.....

Recently, I tested WAKE on LAN on local LAN (where WDM server and client are in the same LAN) and it worked just fine.

But, when I tried to do a WAKE on LAN across WAN (where WDM server and client are connected via VPN tunnel).   It DID NOT work.   I tried putting another client on the remote LAN and tried Relay WAKE on LAN but it did not work also.

How can I wake up a client via remote LAN?

Appreciate the help,