Are the firewalls set to allow such?
Are the addresses proper? (you didn't tell.)
I have a Wanadoo-a789 Model: dv4210-wa as a router and 2 computers both running windows xp and were both reinstalled not long ago, for a while they were able to talk to each other but for some reasson they just can't see each other now, they can't even ping each other.
This is even with the windows and router firewall turned off!!!
Dose anyone now whats happening???