The server port for XMPP (default 5222).
For implicit SSL, use port 5223 (please refer to the SSLStartMode property for more information).
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.