Hi m. hasan,

In order to handle the network disconnect at client side you could leverage the StatusChangeEvent.
By setting a custom handler it is possible to perform actions related to connection and disconnection occurrences.

Please you could also refer to our example "Lightstreamer - Stock-List Demos - Flex Clients" and in particular to the implementation of this method.

Alternatively, if your application runs in a browser, you could rely on navigator.onLine property.

Regards,
Giuseppe