Be very careful while developing application that communicate with Bluetooth / BLE devices and choose Your development platform very carefully.

Lately I did started a personal project to communicate with Bluetooth / BLE device and stumbled upon issues with connectivity. Other, non Qt based, applications were able to connect to the device, but application using Qt were unable even to connect to the device (QBluetoothDeviceDiscoveryAgent was working correctly, QLowEnergyController working correctly, except for…, well, not connecting to the device). This issue was even encountered with my code and simple examples provided with Qt.