When I launch the Windows 10 Mobile Hotspot feature (create a personal wifi hotspot natively) in the Network & Internet parameters, the speed of the connection is normal.
But if I launch any Qt app that link to QtNetwork (with BearerManagement feature), even if the app has nothing to do with wifi, the hotspot speed drop to 0 KB/s for 5 seconds, then return to normal for 5-10s, then drop again to 0 KB/s etc.

If I close the Qt app, the speed never drop again, until I relaunch the Qt app.
The simple fact to launch a Qt app that link to QtNetwork affect the windows hotspot feature.

I've rebuilt Qt without the BearerManagement feature, and no more problem with Qt apps compiled with it.

This affect Qt 5.8, but maybe other versions, I haven't tried. My wifi card use WiFiDirect in order to host hotspot (not HostedNetwork). There's no problem when I use a card that support HostedNetwork as hotspot API. But recent cards support less and less the HostedNetwork API in favor of WiFiDirect.