Bluetooth won't stay connected?

Galaxy S9+ running latest E/OS
Galaxy Tab S2 running LineageOS
Galaxy Tab S7 running stock Android


The S9 phone pairs to my headphones and earbuds, but not to either tablet.
The Tab S2 is paired to the Tab S7 but not the S9
The Tab S7 is paired to both the Tab S2 and the S9
I have reset the wifi / mobile / bluetooth, and rebooted, several times but no luck.

Any ideas?

I had this also on my FP3 and I thought for a long time that this is a problem of my headphones. Sometimes it was really not easy to get a working connection because it always broke down after some seconds.

But then, about a year ago, it got suddenly better. This came by ordinary OS updates, I didn’t change anything myself.

I have it still today sometimes but it’s rather seldom now.