connection breaks

Hi there,

I have a problem with my PPP server running on RH9. It is a dialin 
server. It worked until my ISP decided to change our IP addresses. Which 
I did. Since then I have a funny problem. The server alone can ping all 
servers around the world. But when there is an incoming call which 
connects to it, it cannot see any other computer., ie, I cannot ping any 
other machine. When the connection stops, it can ping again all 
machines. As a consequence my ppp users can only connect but can do 
nothing, they get an ip address but nothing happens. Again it used to 
work fine.

It runs :
- mgetty-1.1.30-2
- ppp-2.4.1-10

Thank you for your answer.