iMac 2017 - Apple Wireless Keyboard 2 and Magic Mouse 2 Bluetooth random disconnects After having the first iMac 2017 Retina replaced for display issues, my second one seems to be acting up.

I use an apple wireless keyboard and magic mouse 2 via Bluetooth. The problem is, they randomly disconnect. Right after the event, a pop-up comes up, trying to find input devices. 

Sometimes they reconnect almost immediately, other times after a while, and others, only a restart fixes the issue. It happens randomly. There are days with no issues and days where it happens so often it drives me mad.

Both input devices work fine when they are connected. The keyboard works after it is disconnected, if I plug it in for charging from the Mac. Can't use this workaround with the mouse, obviously. 

What I tried so far is resetting the Bluetooth module, factory reset devices, disconnect all devices. Nothing seems to work.

OS version is Mojave 10.14.1. It was happening with High Sierra too.

Any ideas besides sending the whole package to warranty?
After spending numerous hours on the phone to Apple technical support, and tried just about every fix suggested here and on othe websites... 

In the process I uploaded some system logfiles to Apple support and after a few more phone calls a Senior Apple technician confirmed that there is a known bug in Apple's Bluetooth drivers which should be fixed in the next patch for MacOS Mojave (which I believe will be 10.14.3). Hopefully this will finally resove the issue.