Bluetooth keyboard standby/sleep too often

Hi, I have a Microsoft Surface keyboard connected via bluetooth. I can pair my PC with it and when it is up it works without problems. The problem is: the keyboard goes to sleep/standby very fast and when I try to wake it up again after a minute ( pressing a button) it takes several tries and seconds to make it reconnect with Manjaro.

I tried Windows 10 on the same PC and the reconnect is way faster. I tried Ubuntu 19.10 live CD and the reconnect is very fast as well. And then I tried Manjaro gnome minimal live cd and I have the same problems as with the installed version of Manjaro => once the device goes to sleep it takes way longer to wake up.
Sometimes after a long time (30 minutes) without use, even pushing the buttons repeatedly wont wake up the keyboard, which means I have to reboot. It may be a hint, but when the mainboard goes to sleep, the bluetooth sign in the upper right corner disappears.

I would appreciate any help.

kind regards,
Bernd

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