When updating from Qt 5.9.2 to 5.9.3 today, our UDP based network protocol stopped working on Windows 8.1!
The reason is that QUdpSocket::readDatagram() does not assign the sender address any more.
Here is some example code that fails with 5.9.3:
So sender.isNull() returns true, which should not be possible!
The same code is still working on Linux and Android.
Fortunately using QUdpSocket::receiveDatagram() instead seems to be working.