void loop()

 
In my case, it centers the joystick values (which programmatically stops the tracks as the following code takes those values and controls the motors) and flashes the headlight to signal loss of connection to the App.

  // Connection Failsafe
  if (RemoteXY_isConnected() == 0) {
    RemoteXY.joystick_1_x = 0; // Set for dead stop
    RemoteXY.joystick_1_y = 0; // Set for dead stop
    // Flash headlamp LED when App not connected.
    digitalWrite(PIN_LED, !digitalRead(PIN_LED));
    delay(500);
  }

Insert this at the top of your void loop.

void loop()
{   
  RemoteXY_Handler ();

  if (RemoteXY.connect_flag==0){
 
  digitalWrite(PIN_SWITCH_1, LOW);
 
}
  else

  digitalWrite(PIN_SWITCH_1, (RemoteXY.switch_1==0)?LOW:HIGH);
}