My wireless keyboard is:

Advent wireless keyboard
Model advkbwls
Sn 1908047499

I am having issues with it on my fully upgraded Ubuntu 19.10.
After login I am able to write perfectly. But after some random amount of time the keyboard isn't reacting. Well, it just needa a long time to think about the keys I've pressed. Hence the sentences becomes very unusable. Sometimes the letters isn't printed on the screen. If I wait 10 seconds then suddenly all the letters are printed. But in an random order. And some of the letters up to 4 or 5 times in a row.

I thought it might be an issue about the driver. So I tested in Windows 10. In Windows 10 a new driver was automatically installed. And I experienced no problems regarding typisk sentences. Well, I didn't test it for a long time (because I am not using Windows 10). So it was just a very short test if the same issues seemed to emerge in Windows 10.

Does anybody have a suggestion about what I am to do?

I am using kernel 4.19.21 or close to. I have no option of upgrading to 5.* because that will destroy the stream of data between my host-system and my quest-system through KVM.

Thankyou in advance!