This API would work something like QNetworkConnectionMonitor. Letting the user create and 'subscribe' to updates on the reachability of a certain IP/hostname.

In my opinion this one is not and should not be a priority as it only has proper OS support on Darwin platforms. Any other platforms would, at best, just notify if the local IP used in the connection lost connection (as was done in the Windows implementation for QNetworkConnectionMonitor), but that's not optimal.

Unless there're more platforms where it can be implemented properly it may be best to leave this unimplemented (leaving users to use the platform API on Darwin).