This may be old thread but I thought I might share a bit.
Maybe could help others.

I got WOL and WOL-WAN working with the D-Link DIR-615

Just like others I could do it within the same network but the when on other network it not working.

After a bit of googling, I saw that Tp-Link needed ip/machine binding or something for it to work over wan.

But now dir-615 does not have ip/machine binding nor virtual servers.

Ok so what I did was simply add my machine number, ip and port to advanced >> filter rules and allow it. and boo ya.. it worked.

may be this help those who want wakeup over lan over wan for the dir-615.

if need the complete guide then just pm me. Maybe I will post it.

IMHO, the dir-615 is not that bad considering the price and value.
I got it free with my unifi and I feel it is a good router albeit the new ones that is given is even worst.
Good day.