Multi-play over the WAN is a problem only because the built-in commands were not designed to do it. The original intention was that they were only for network-based games running on the same sub-net.
The reason they don't work over the internet is that the commands use DirectPlay and there is no way to select which port on your router you want to use.
Experiments I did when writing the tutorial suggest that random ports are used so you can't just use one which happens to be chosen and hope the same port will be used next time. It won't.
So, for it to work, you would have to get
all players to disable any software firewalls and open
every port on their routers - and you would need to be rather stupid to do that. I wouldn't anyway...
The external addons people have created to do the job have one important addition to the built-in commands... port selection. You select the port number (which it sticks to), make sure that port is open on your router and away you go.
There really isn't much else you can do.
TDK