"Connected" timeouts indicate that the connection to the real server has been established and that data may have been transferred. The connection was disconnected because the idle timeout has been reached. This type of timeout is normal and is mostly the result of clients simply abandoning the connection.
The default for the timeout is 660s. This timeout can be found in System Configuration > Miscellaneous Options > L7 Configuration. The 'L7 Connection Timeout (secs)' is the global value for this timer. If it is set to 0, it will use the default value. This value can be overridden by the 'Idle Connection Timeout' in each virtual service.