Robert
Well, if you think about how the netmask is used to route an Ip address out to the LAN or to the WAN, then the problem is obvious, as the internal "gateway" in the SMEServer (the WAN NIC) is apparently a LAN address and therefore not routed to the WAN side. I can't see how else it could work..
I also made this mistake in the early days, but it did not take me 6 days to find the problem - only a few hours!!
I promise you that SMEServer is worth the effort, I have around 15 "out on the field", and there are people here with hundreds of the things in service.