Jim McBeath wrote:
> 
> Ah, I get it!
> 

Yes you did!

> It seems that it doesn't really matter what subnet and IP 
> address values I choose for the PPTP server and its clients, 
> as long as those addresses don't conflict with anything else 
> on my network.  I tried using addresses from my LAN subnet, 
> and I tried using addresses in a different subnet, and it 
> works the same either way.

That is almost true, i think you need to be in your LAN range
for NAT to work correctly...

> 
> Any suggestions as to what might be wrong here, or how to debug?
> 

enable logging for all rules for your PPTP and Wireless interface
(both pass and block rules).

Magne