The port of the MQTT server (default is 1883). The default port for SSL is 8883.
This property specifies a service port on the remote host to connect to.
A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.