Windows Update sometimes overwrites the custom CSR driver with a generic Microsoft driver that breaks functionality.

Up to 2 Mbps, doubling the throughput of Bluetooth 4.2. Interface: USB 2.0 / 3.0 Type-A.

Avoid Windows XP/7 generic drivers from unknown CD-ROMs included with the dongle – they often contain malware.

~40% for generic E-UB5 dongles. If this fails, proceed to manual methods.