Not sure why people cant connect to local servers? is it the firewall?

[killstreak1597]

I have a local teamspeak server that has been port forwarded. My problem is that people on the local network can't connect to the server using a local ip, while people can still connect via a external ip from outside the network.

Is there something that is restricting data between computers on the network?

if it helps I'm running a squid proxy in transparent mode.