Yes and would be because there is no such thing as wake on "WAN" or internet.
Anything you see that talks about port forwarding is not valid really. WoL has no concept of IP address or ports. It sends a packet to the broadcast MAC address containing the MAC Address of the device to wake in a special pattern.
So it is immediately impossible since mac address can not pass off the local lan segment.
Best option is to get a router that has a special software option that lets you remote into the router and ask it to send a actual WoL packet. Many asus routers have this feature.
The key problem with using the port forwarding hacks is they ignore the problem that the ARP times out in the router. The ARP is what maps a mac address to a IP.
The only way to make a hack like this to work is if your router supports static ARP entries. This is something you generally only find on third party firmware. If you even think to pursue this find a reputable site that discusses setting static arp not some stupid one that think you can just port forward.
In general some of the microsoft sleep options are just as good as WoL. The power difference between a machine being in sleep mode compared to being in the off mode WoL uses is very small.