I believe that his netmask would actually be 255.255.0.0, so he's good to go on that point, as long as all of the nodes understand this properly.

If I recall correctly, there was a problem once upon a time where even a 255.255.0.0 netmask wouldn't work, and the player still had to be the same first three octets as the computer.

It might have simply been a bug in an early emplode that's long since fixed, but that's what my memory tells me.

In any case, his problem has been solved by using a different hub, so it's all moot now.