I have two Asterisk Boxes. For testing they are both on the same network sitting side by side to each other. IP’s are 192.168.1.150 and 192.168.1.10
System 1 is running on a Raspberry Pi 4 with no issues, all the extensions can call each other and the audio is great. Extensions are 500-510
System 2 is running on a full size machine also with no issues between extensions calling each other. Extensions are 400-410
I have an IAX2 trunk between the two boxes, I can be at System 1 and dial a 400 Extension and they will ring and can pick up the call. If someone from Extension 400 talks in the call then person from ext 500 can hear them, but if person from ext 500 talks, person at ext 400 hears silence. So its a one way audio issue.
I did try changing the allow=ulaw to something else and when i did all calls between systems would drop.
Here are the Peer Details from System 2
Peer Details from System 1