It is so much easier than all that.
Part 1:
Go to Services DHCP Server and scroll to the bottom.
Add a DHCP Static Mapping for the device. While doing so, in the Edit static mapping page select the "ARP Table Static Entry" option. Not to be confused with the "Static ARP" option on the main Services DHCP Server page.
That will cause an ARP table static entry to be created and will survive reboots, updates, etc. because it is saved in the config.
Part 2: (optional)
To forward WoL packets through the NAT from the outside. Create a static mapping for MAC FF:FF:FF:FF:FF:FF with an IP address of something like maybe 192.168.1.254 for example. Because *.255 (broadcasts) won't be forwarded. But *.254 will be.
See screen capture attachments.
With this set up WoL magic packets sent to the WAN address on the specified UDP port are forwarded as a broadcast on the LAN.
Restriction to trusted source addresses and networks is highly recommended.
Snap1.jpg
Snap1.jpg_thumb
Snap2.jpg
Snap2.jpg_thumb
Snap3.jpg
Snap3.jpg_thumb
Snap4.jpg
Snap4.jpg_thumb