"some" ppl can't hear eachother

[Ultimatom]

Hi all,

i have a server set up on my pc ..my friend connect and i can hear them and they can hear me. The problem is 2 friends of mine that live together ..1 can hear the other but the other can't hear the 1st one :eek: . They are on a network obviously and none of them is on mute.
Me = hear and talk to everyone
friend #1 = Hear and talk to everyone
friend #2(roomies of friend #1) = Can't hear friend #1 but can talk to everyone

If anyone can help me with this i would be very happy :D

Thank

[m&m's]

sounds like there router cant foward the same thing to 2 lan ip's at 1 time