How to set up a static ARP entry on the router

[Enej]

Hello!

I recently made my PC Wake on lan fuunction and everything is working great,

but when I am away from home and I want to wake it, it doesnt wake (I have HTC ONE X - Android with Splashtop application and I am on 3G network)

It only wakes up when I am at home. When PC is ON, I can access it through my android phone and operate it, but I cannot wake it up.

Edit: I have Asus WL520g router

Any help please?
Thank you

 

[Agent Smith]

I might need to access remote management or some other option to allow external IP address access.