11-21 10:59:09.231: D/SMACK(712): RCV (0): </stream:stream>
11-21 10:59:09.233: D/SMACK(712): SENT (0): <presence id='EvQ7X-6' type='unavailable'></presence>
11-21 10:59:09.234: D/SMACK(712): SENT (0): </stream:stream>
The server sends a closing stream element, on which Smack also closes the connection. You have to "ask" the server why it does that.