I find a solution for this problem. I have this keyboard connected to a Desktop running the Windows 10.
First open the Device Manager and find the main bluetooth driver in the "Bluetooth" tree.
In my case it was "Dell Wireless 1801 Bluetooth 4.0 LE".
Then access the driver properties (right button > Properties).
The evidence to know if the chosen driver is the main bluetooth driver is that the properties window has a "Power Management" tab:
Then go to this tab and UNCHECK the option: "Allow the computer to turn off this device to save power":
Click in "Ok" and be happy! I tried a lot of things, and only this worked for me!!
I disabled this option too in an other driver that I find (see below), but I dont know if it needs to solve the problem.
So, that is it! Good luck and let us know if this solution worked for you!!