I'm seeng a very strage behavior sometimes when I have my exernal IP changed by my ISP.
I have detected the problem in my SIP VoIP providers, but may occur to any other service, (my guess)
Normally, outgoing SIP packets viewed in the pppoe interface have the ISP assigned public IP in the source address IP header.
But, upon a WAN IP change, I have some packets (sometimes for all of my providers, sometimes only for one or two providers) getting the PRIVATE IP Address (192.168.200.3 in my case) in the source address IP header on the outgoing interface!!
Obviously packets exit the router to never come back, and thus the VoIP provider gets marked as unreachable by my Asterisk PBX.
I tried restarting the firewall, but no luck... Any idea on why this is happening or how can I avoid or ease this problem?