The MinPort property specifies the minimum range of port
numbers that will be used with passive data connections. A value of
zero specifies that the default value of 30000 should be used. The
minimum value of this member is 10000 and the maximum value is 65535.
If the value is non-zero, it must be less than the value of the
MaxPort property.
Attempting to change the value of this property after the server
has started will cause an exception to be raised. To change the
minimum port number for the server, you must first call the Stop
method which will terminate all active client connections.