Like a lot of folks I would get errors while using Pat to do winlink messaging.on packet
The symptoms were various time outs, and always when large messages were involved.
I did a lot of troubleshooting, doublechecking settings, reading multiple articles on ax25 etc...
During all this it was recommended to monitor axlisten
$ sudo axlisten -a -r -t
axlisten as listed above will show the outgoing and incoming packets.
While doing this I noticed a lot of packet repeats...ignored calls and rejected packets...and eventually it would timeout.
On a guess, I thought maybe I was overdriving the audio...same settings I had been using since I got it working initially, and that had worked for shorter messages.
So I lowered the digital gain to 0.
I continued to monitor the axlisten and pretty much all of the errors went away...sure there is an occasionally repeat, but not constant repeats, and no ignored responses.
So for those of you struggling with this...monitor axlisten and if you see lots of RRs and REJs then you may have an audio problem...
It would be obvious if I turned the gain too far down...then the receiver never would have responded to my packets.
You don't need to actually be doing any transmitting to use axlisten...it will here any station on that freq sending and receiving messages...that was part of the clue, those messages (other stations traffic) were much cleaner than mine (no rejected packets...quick responses)