Level 1

37 points

Bluetooth devices connect and disconnect at random

Purchased a new iMac (Retina 5k, 27-inch, 2017, MacOS Mojave) last week and it has been a nightmare.

The bluetooth mouse and keyboard randomly connect and disconnect. Without having wired versions attached, the system would be unusable.

So, I've reset the PRAM and SMC a few times to no avail. Then I called Apple Support for some less than useful advice. They had me create a dummy account to see the the problem still occurs - it does. Oh, and then I was supposed to boot in safe mode. Well, I restarted my system, holding the shift key as directed and the system had still not booted after 10 minutes.

Any suggestions or should I just demand my money back?

iMac with Retina 5K display, macOS Sierra (10.12.4)

Posted on Oct 11, 2018 9:06 AM

Top-ranking reply

MacOde

Level 1

19 points

Posted on Dec 21, 2018 5:42 AM

I have made *some* progress on the issue. As I mentioned in my previous post, USB 3 devices are known to interfere with other wireless devices. So I added a long shielded extension to the the USB 3 port I was using to get the my 3.0 hub farther away from the mini. I switched to USB hub with an external power supply. I took advantage of the USB 3.0 hub in my monitor (connected via thunderbolt). Finally, I moved the mini away from other nearby devices. All this made a significant improvement in bluetooth performance. Not sure which was the critical change since I did this all at once as part of reorganizing all of my USB devices. While not perfect, my Magic Mouse tracks much better, the keyboard works reliably and the mini usually unlocks with my watch. All of these functions were significantly degraded prior to these changes. Of course YMMV.

I think the underlying problem is that there are limited locations within the mini to put the bluetooth antenna and there are a lot more high frequency connections (i.e. fast I/O ports) that might produce interference than previous mini's.

View in context

24 replies

rkaufmann87

Level 10

148,458 points

Oct 12, 2018 6:35 PM in response to JimHardy

JimHardy,

No point in ranting about the lack of service you have received. That is not constructive and doesn't win you any friends.

Un-pair all Blue Tooth devices. Turn off Blue Tooth, restart in Safe Mode, Turn Blue Tooth back on, re-pair all Blue Tooth devices. You will need a USB keyboard and mouse to do this. If you don't have these, beg or borrow or even better buy a pair.

Oct 31, 2018 1:22 PM in response to JimHardy

Unfortunately this does not surprise me. The endless lack of a software fix for so many made me feel it is a hardware issue. It is driving many loyal customers crazy. A cheap Bluetooth dongle could fix it easily I suppose but apple will never do it. A shame. Worse, daily annoyance.

Nov 2, 2018 9:28 AM in response to Gijs Raggers

Today I bought an ASUS USB-BT400 bluetooth dongle. Now the bluetooth connection to the mouse and keyboard are working flawlessly again. Hurray. I had to enter this in Terminal to make the ASUS dongle the main bluetooth connection:

To force the system to use USB Bluetooth dongle by default, run the following command:

sudo nvram bluetoothHostControllerSwitchBehavior=always

^{This will modify your boot kernel arguments.}

To do opposite, use never. The change would be applied after the reboot. To return to the default, run:

sudo nvram -d bluetoothHostControllerSwitchBehavior

Beoze

Level 1

4 points

Jan 22, 2019 3:36 AM in response to JimHardy

This is a hardware failure. The bluetooth module is defective. Apple is aware but they will never admit it. If you want to solve, buy a bluetooth dongle or a logitech mk850 keyboard or mouse combo or similar

Old Toad

Level 10

215,352 points

Mar 15, 2019 12:04 PM in response to JimHardy

Safe Mode boot will take up to 10 or so minutes as the system is verifying the startup drive, repairs any directory issues and deletes several cache files. So let it finish and it'll get booted up.

Did you purchase the iMac directly from Apple or from a 3rd party? If from Apple and it's been less than 14 days since you purchased the iMac you can return if for a full refund no questions asked.

skiab0x

Level 1

4 points

Jan 15, 2019 1:03 AM in response to Gijs Raggers

Does it work with Mojave sir?

Thank you!

Roastman

Level 1

18 points

Jan 15, 2019 1:29 AM in response to skiab0x

Not on my iMac 🙁 (response to: doea it work on Mojave)

skiab0x

Level 1

4 points

Jan 15, 2019 8:01 AM in response to Gijs Raggers

Can you use Asus USB-BT400 before giving the 'sudo nvram bluetoothHostControllerSwitchBehavior=always

' command?

MacOde

Level 1

19 points

Jan 15, 2019 8:09 AM in response to skiab0x

I the "IOGEAR Bluetooth 4.0 USB Micro Adapter, GBU521" from Amazon and it worked for the mouse and keyboard, but it does not work unlocking the computer with the Apple Watch.

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

Bluetooth devices connect and disconnect at random