I'm pretty sure no inexpensive commercial home router is going to support recieving subnet directed broadcasts from the Internet, since doing so would offer a trivial vector for allowing DoS attacks. (I imagine most if not all ISPs filter such things at a higher level anyway.) Also, 99.99995% of the time someone with a home network is going to be using RFC1918 addresses with NAT internally instead of public IPs, so from outside on the internet even if you could send a directed broadcast as far as the front door of the router the RFC1918 network on the inside where it has to be ultimately converted into a true broadcast packet is going to be unroutable.

I do... have to say I'm a little confused about what you're attempting. Is it that you want to send a WOL packet from somewhere on the internet to your sleeping machine at home directly, or did you want to have the Newton sitting awake inside your network and listening for the wake signal through your router (presumably listening on some TCP port forwarded through and aliased to your public IP), which upon reciept would itself send the wake packet to the sleeping server? If it's the latter a Newton is probably going to be a "challenging" platform to set up to do what you want.