Problems connecting mouse and keyboard

Ever since I installed MacOS Mojave (now 10.14.1) I have been having trouble connecting the Apple mouse and keyboard. Both had always been working fine (over a year).

Now they don't connect or lose connection when the mac wakes up. Sometimes they reconnect after a few minutes.

I have tried all the obvious thing like deleting the bluetooth list in Library/Preferences, but the problem hasn't gone away.

Sometimes it works, then the connectivity fails again.

It's very annoying, the only saving grace is that I have a spare wired mouse lying around, but that can't be the solution.

Any ideas?