If the status LED does not flash in white even when you open the lid of the charging case, the earbuds are not in the pairing mode. With the lid of the charging case left open, long press the multi-function button on the back of the charging case for approximately 2 seconds to switch to the pairing mode.

Select A2DP as the Bluetooth connection profile on the transmitting Bluetooth device. For details, see the Owner’s Manual of the Bluetooth device.

Further troubleshooting

Re-start your Bluetooth device and try pairing your earbuds with Bluetooth again.

If you’ve previously paired your earbuds with Bluetooth, then remove your earbuds from your Bluetooth device’s paired device list and try pairing again.

Make sure that the earbuds are updated to the latest version using the Denon Headphones app.

Restore the earbuds to their factory settings. link

Cannot connect to LE Audio

To connect to LE Audio, an LE Audio-compatible Bluetooth device is required. Also, even if a Bluetooth device supports LE Audio, settings may be required to enable LE Audio. For details, see the owner's manual of the Bluetooth device.

Enable the LE Audio setting using the Denon Headphones app. After changing the earbuds' LE Audio setting, delete the connection history for “Denon AH-C840NCW” in the Bluetooth device's connection settings once and then pair again. link

When the earbuds' LE Audio function is enabled, Swift Pair is not available for LE Audio connection. Connect the earbuds using the connection settings of the Bluetooth device. link

Make sure that the earbuds are updated to the latest version using the Denon Headphones app.

Even with LE Audio-compatible devices, connection and operation may be unstable depending on the device. In this case, disable the LE Audio setting in the Denon Headphones app or restore the earbuds to their factory settings. link