Linux: Manually disconnect if ping/pong does not react within proper time

I run the simpleclient example of QtMqtt. As shown in attachment. at 13:42:37 I unplug the ethernet cable from my computer.  QMqttClient should emit the signals stateChanged and disconnected after 60 seconds(the default keepAlive).But it emit the signals until 13:59:09. No such bug on windows.