I'm assuming that 0.95 is a version just from the look of it, and the fact that it gets sent at the beginning of proceedings.
I was wrong on my previous post about what constitutes a "connected" status in aunetsend - the relationship between the data and the status is:
Listening - waiting for a TCP connection
Connecting - TCP connection has established, "ausend 0.95" sent, waiting for "aunetrecv" reply from aunetreceive
Connected - "aunetrecv" has been received, now streaming audio
If the aunetsend stays at "listening" then nothing is getting through from aunetreceive. There must be something stopping the connection being made. Try this: on the aunetreceive machine, go into Terminal and type
nc xxx.xxx.xxx.xxx 52800
where the xs are the IP address of the machine running aunetsend. That should cause the aunetsend to change status to "Connecting".
If it stays at "Listening", then there must be a firewall or something running.
I didn't realise that you were going to try installing the .component file as a plugin! Interesting that it changes something. The coreaudio.component file is basically *all* of CoreAudio. Plugins, default sounds, all that stuff. I was suggesting taking that file and copying it to the same location on one of the machines that didn't work, thinking that there was a version mismatch between the protocols.
I do like a good investigation! good luck