I’ve recently upgraded my MacBook Pro to a shiny new 2015 model running OSX El Capitan. Around the same time I bought a Microsoft Designer Bluetooth mouse (part of the reason I upgraded my MBP was because the Microsoft mouse required Bluetooth 4.0 – which didn’t work on my 2009 MBP) – and most of the time the Bluetooth mouse worked fine…
That was until I decided to play music through my Bluetooth Speaker at the same time.
No matter what I did, where I looked on Google, the Microsoft Mouse would disconnect regularly – like every few seconds. Deleting com.apple.Bluetooth.plist did nothing. Restarting the MBP, resetting the SMC, re-installing El Capitan… Nothing. Worked fine under Windows in Bootcamp so I was suspicious that all the hardware was fine but the problem was in OSX itself.
Turns out it, it probably is…. I found the gem finally – disable the Handoff feature – here’s how;
1. System Preference –> General
2. Uncheck “Allow Handoff between this Mac and your iCloud devices”
3. Restart your Mac.
Since then the mouse has worked like a charm, even with the music blaring!
Massive thanks to Michael Kummer for his post providing this information at https://www.michaelkummer.com/2015/10/08/troubleshooting-os-x-bluetooth-issues/