Switching network type causes a preconnected QNetworkAccessManager to go into the NotAccessible state

When the phone is connected to wi-fi and 4g, and the user disable the wi-fi the QNetworkManager instance will go into the NotAccessible state, if it was previously connected to an host (connectToHost/connectToHostEncrypted).

Steps:
1) enable both WiFi and 4G (it's important that both are enabled before opening the app);
2) open the app;
3) disable the wifi;
4) the QNetworkAccessManager goes into NotAccessible state.

It might be necessary to try 3-4 times, as it doesn't happens always.

Also, I'm not sure if it's related, but just before switching state, I see the following log message:

QObject::disconnect: Unexpected null parameter

It appears to happen only on iOS, I tried on a Samsung Galaxy S6 (Android 6.0.1) and I couldn't reproduce it. Also it doesn't happen if the manager wasn't connected to an host.

Attached there is a test application to reproduce the issue.