> DNS servers with no problem.  After using tcpdump to monitor activity on my internal
> interface on the router, fxp0, it shows that the responses never make it back to 
> this interface.  The responses do make it back to the ppp0 interface though.

A nearly identical setup works for me.

Can you show a tcpdump on both interfaces
(like "tcpdump -i ppp0 -vvv -s2000 -l | tee /tmp/log.ppp0" and 
"tcpdump -i fxp0 -vvv -s2000 -l | tee /tmp/log.fxp0" )
when this happens and the output of "ipnat -l" on the NAT router?


Martin