Q: Bluetooth disconnecting, possible corrilation to external usb hard drive

  We purchased a new iMac Retina 5K 27" Late 2015 when it was released. Since day one we have been battling an issue where the bluetooth disconnects, Magic Mouse 2 and Magic Keyboard are disconnected, then reconnected. The mouse will freeze, and about 3-5 seconds later the "connection lost" notification will flash up on the screen, followed by the reconnection and will begin working. The entire span of not being able to use the mouse and keyboard will last about 7-10 seconds. It happens randomly, maybe once or twice a day, maybe more.

  I've opened two cases with Apple support, the first they had me reset SMC, PRAM, a bunch of stuff. It didn't really seem to improve it. The second said to reinstall the OS, "do a reset". I have yet to do that, mainly since this is a brand new PC and has had the issue since day one.

  Today I noticed the Time Machine backup seemed to start right around the time the bluetooth connected. We have two new Western Digital USB hard drives connected, one is formatted HFS+ for the Time Machine backup, the other ExFAT for media and extra space. Could the external USB drives be causing the bluetooth disconnection since bluetooth seems to be connected through the USB controller? If so, how do we correct this without disconnecting the USB drives? It seems like they shouldn't cause the bluetooth or USB to reset!!

For such an expensive computer, this issue is extremely frustrating considering Apple support has been unable to resolve. Any help or suggestions appreciated, thanks!

Journaled HFS+

  Device Name: My Passport 0829

  Media Name: WD My Passport 0829 Media

ExFAT

  Device Name: My Passport 0827

  Media Name: WD My Passport 0827 Media