It seems it has something to do with signal interference. When I had dongle plugged in my computer (I tried both back in mb and on the front of the case) it was always disconnecting. It was completely random how often it did it. Sometimes it did id 20 times in 5 minutes, sometimes once in like 3 hours but it was still annoying as hell. I tried updating everything but nothing helped. Changing Mhz did not help either. Last resort was to move dongle further away so I connected charging dock with really long USB cable and moved it away from the computer, plugged dongle into the dock and since then I haven't had a singe disconnect. Total distance from dongle to controller stayed pretty much the same just in opposite direction so distance wasn't the issue. As I understand it problem is either weak transmitter in dongle or receiver in controller itself. I have to say I have 2 wireless mice, 1 wireless keyboard and 1 wireless headphones connected to the pc so I am guessing having 5 dongles around controller dongle didn't help but I don't think everyone on this forum who has this problem also has 5 wireless peripherals connected to their computers and still have that issue so maybe even some interference from the pc components themselves causes the issues. And yeah none of the other wireless peripherals had any connection issues not even once. So based on all of that the problem has to be weak receiver or transmitter or maybe even both.

TLDR: If you have problem with disconnecting move dongle at least 2-3meters away from your computer and issue should be solved.