ESP8266 WS Server don't recognizing android client's disconnection

[ghost]

I have create a Android App(WS Client) which I use Autobahn Library. In ESP8266(NodeMCU) I have the WebSocket Server with library arduinoWebSockets. My problem is when I am connected to the AP and then close the Wifi and disconnect from access point in Android the ESP don't recognize the disconnect.

Why this can happen ?

Thanks!