The Server class (and a few other places like SaslFactory) have behavior which depends upon there being more than one connection available. In these cases the code will violate Law of Demeter and call Acquire() off of the ConnectionPool property of the IOService implementation. The problem is that muxio will call Acquire() when MultiplexingIOService ctor, emptying the pool if the MaxSize/MinSize is 1. In order to work correctly, the MaxSize must be at least 2.
The work-around is to just use the default MaxSize/MinSize or whatever values that these settings have as long as the are no lower than the defaults.