What would make double NAT fail? fyi: works in my home just fine though two Linux iptables setups for something I was playing with. Then again NAT on Linux may be better than that in a hardware firewall?
Hmmm what's the association with the MTU setting? And just where is this set in the dsl modem and in windows? "just works" with Linux... too bad this system isn't fully under my control to do "right". How do you find the "right" MTU setting?