Long story short, my bluetooth mouse, a Logitech Mx Master 2S, disconnected out of the blue, first times I just had to turn off and on bluetooth on windows, once the bluetooth device was automatically disabled because “it caused problems” and I had to restart, finally it stopped working altogether, always telling me “try connecting your device again”. I tested it with every other bluetooth device I had handy, to no avail.
Wasted maybe half an hour, on my almost nonexisting free time schedule (AAARGH)
So finally I had the nice thought of checking, from device manager, if there were updated drivers for the chipset responsible for wireless (WiFI and Bluetooth), a Centrino Advanced-N 6235. I updated it since it automatically downloaded new drivers, restarted as I was asked, and even if wifi kept being shitty, the bluetooth mouse finally connected, as did my android phone.