Bluetooth enabled keyboards and mice may not pair or connect consistently, or audio from Bluetooth enabled earphones or speakers may be choppy. This can happen if certain external USB 3.0 devices are too close to your Mac.
● Try moving external USB 3.0 devices further away from the computer, and away from your external Bluetooth devices. For example, if you think an external USB 3.0 hard drive may be causing an issue, try relocating the device away from your Mac or move it to another side of your Mac.
● Make sure all USB cables are connected correctly. Better shielded USB 3.0 cables may also be helpful.