Everything is exactly the same on the macs and pcs. Everything works (limewire, ftp, irc...) until we enable the firewall that's built into the router. Then, only the PCs can connect.

In theory, the firewall should only be blocking incoming calls to a specific port (6346 for gnutella for example). So enabling the firewall and allowing incoming tcp and udp traffic at 6346 on the firewall should allow gnutella to continue working. But it's not working.

It can't be anything wrong with our isp since limewire connects until the firewall is enabled. It can't be the firewall on the macs because there isn't a firewall running on the macs. The only firewall that's running is the one built into the router. It shouldn't be the config of the macs either since they are able to connect with the firewall turned off and I can surf the web even with the firewall on..