System time change is described here. Might be related to the disconnect as timers might be fired at a different time and you might get a heartbeat timeout.
This "Disconnect in Progress, try later" is thrown when the previous TCP connection (the rep channel) is not fully disconnected. You will see this messages until the disconnect is finished.
"Software caused connection abort" is related and usually thrown when the server socket at the other instance has no space in its accept buffer, that is, cannot accept connections at this time ("Disconnect is in progress").
So my guess is that it is related to the system time change which is a delta of about 28 seconds.