Can only hear one other musician in group

[mlynch66]

I have a Mackie fx12 v2 board with the built in audioface running into a Macbook air. I can only hear my drummer! He can hear everyone else and they can hear me with the exception of the sax player who sounds like squi$ng water when he plays or talks. Very frustrating! Have spent much time trying to fix this. Did the Port Forwarding thing on my router but did not change anything. Had the same setup last winter and it worked fine with the same folks. Restarted many times, tried different hosts and even uninstalled/reinstalled  software. No change. I have good internet speed and good numbers with latency and jitter. About to drop $10,000 on heating my barn and have live practice! please help I would appreciate it.