I'm enjoying VarAC - the functionality is very good and it works well with reasonably strong signals. But the underlying VARA protocol seems to get in the way as the signals drop. I'm an old-time PSK31 and RTTY user - zero error detection and correction. I could manage a QSO under some pretty terrible conditions - it's surprising how much corruption to the data stream you can accept and still work out what the guy at the other end means. I'm finding that many of my VarAC QSOs fail because the signal drops down into the noise floor and VARA goes into a sequence of repeated NACs and retransmissions. If I look at the monitor window, I can see that most of the text is getting through but it's failing the data integrity checks. I would settle for some garbled text rather than a dropped connection!
Does the client application - VarAC in this case - have any control over the low level protocol? Are you able to do anything to accept the errors and let the QSO continue?