Eu tive um problema semelhante ao seu, e usei uma página da Web no meu servidor para enviar o pacote mágico.
Eu usei o código e o WolAsp.dll de Depicus :
Wake On Lan for Active Server Pages allows any IIS web browser with the ASP interpreter to send a Magic Packet to a remote machine
Na página de perguntas frequentes:
Wake on Lan over the Internet (or why is it such a pain in the ****)
"IP directed broadcasts are used in the extremely common and popular "smurf" denial of service attack, and can also be used in related attacks.
An IP directed broadcast is a datagram which is sent to the broadcast address of a subnet to which the sending machine is not directly attached. The directed broadcast is routed through the network as a unicast packet until it arrives at the target subnet, where it is converted into a link-layer broadcast. Because of the nature of the IP addressing architecture, only the last router in the chain, the one that is connected directly to the target subnet, can conclusively identify a directed broadcast. Directed broadcasts are occasionally used for legitimate purposes, but such use is not common outside the financial services industry.
In a "smurf" attack, the attacker sends ICMP echo requests from a falsified source address to a directed broadcast address, causing all the hosts on the target subnet to send replies to the falsified source. By sending a continuous stream of such requests, the attacker can create a much larger stream of replies, which can completely inundate the host whose address is being falsified.
If a Cisco interface is configured with the no ip directed-broadcast command, directed broadcasts that would otherwise be "exploded" into link-layer broadcasts at that interface are dropped instead. Note that this means that no ip directed-broadcast must be configured on every interface of every router that might be connected to a target subnet; it is not sufficient to configure only firewall routers. The no ip directed-broadcast command is the default in Cisco IOS software version 12.0 and later. In earlier versions, the command should be applied to every LAN interface that isn't known to forward legitimate directed broadcasts."
Quoted from Cisco.
Eu me pergunto se em algum lugar ao longo da linha, o pacote está sendo bloqueado. Você pode tentar WoL do Depicus 'na página da Internet e ver se o pacote chegará ao seu computador.