This "Non-Fatal Error SSL channel "sock..." error. wrong version number" happens, when old not supportable farmerswife (fw) Client applications try to log-in to a fw Server running on v6.4 or later:
This will happen if the fw Server is on v6.4 and the fw Client desktop application is running on a version below v6.1.
You will need to figure out which user is trying to connect from which machine which has an old, below version ... and not yet have a manually upgraded fw Client application installed.
Then manually upgrade the fw Client application.
Direct links for the v6.4 fw Client installers for all platforms: