| Problem | Solution | |---------|----------| | Device not detected | Try a different USB port (preferably USB 2.0 if USB 3.0 fails). | | Driver installs but Bluetooth doesn’t work | Uninstall any existing Bluetooth drivers (like from Intel or Broadcom) first. | | “Driver is unsigned” error (Windows 7/8) | Restart and disable driver signature enforcement (press F8 during boot). | | Can’t find the device in Device Manager | Check if the LED on the dongle lights up. If not, test on another PC. | | Bluetooth mouse/keyboard lag | Install the latest driver from Realtek (v1.9+ recommended). |
Linux integration relies on kernel modules and firmware blobs.
Kernel Support:
The RTL8761B chipset is supported in modern kernels (5.x+). The driver module is typically btusb.
Firmware Installation: If the device is recognized but fails to pair, it usually indicates missing firmware binaries.
If you have followed all the steps and the UGreen CM390 still disconnects randomly or fails after sleep, you need to disable USB selective suspend. ugreen bluetooth 50 usb adapter cm390 driver install
4.1 Error: "Windows has stopped this device because it has reported problems (Code 43)" This is a generic failure signal. In the context of the CM390, this usually indicates a driver version mismatch. Resolving this requires a "clean install" of the driver, ensuring the specific Realtek driver overrides the generic Microsoft driver.
4.2 Audio Stuttering (A2DP Issues) If the driver is installed but audio playback on Bluetooth headphones is choppy:
4.3 Pairing Failures Older Bluetooth caches can prevent successful pairing.
While Windows 10 and 11 possess an extensive generic driver database, the CM390 often requires the specific Realtek Bluetooth driver to enable 5.0 features such as Long Range (LE Coded PHY) and High Speed (2 Mbps). | Problem | Solution | |---------|----------| | Device
Phase 1: Pre-Installation Cleanup System conflicts often arise if a previous Bluetooth driver is present.
Phase 2: Driver Acquisition Because UGREEN acts as the OEM, they host the specific driver binary on their support servers.
Phase 3: Manual Installation (The "Solid" Method)
Phase 4: Validation Upon successful installation, the device manager should display "Realtek Bluetooth 5.0 USB Adapter" under the Bluetooth category without yellow exclamation icons. The "Services" tab in the device properties should list active services (A2DP, Handsfree, etc.). Phase 2: Driver Acquisition Because UGREEN acts as
Cause: The CM390 uses a hideable boot mode. Some apps (like Bluetooth tray apps) hide audio devices.
Fix:
Before installing the driver, complete these three steps to avoid conflicts: