Bluetooth earphones sound stops after a while in call

Hi all! I am having a problem with my blue tooth earphones and dell XPS 15 9500.

Specifically, they are connected normally and work fine when I am listening to music or watching videos; I also have my blue tooth keyboard connected. But while in a call (e.g. messenger, Zoom, Google Meets) after a specific amount of time (approx. 20 mins) the sound stops abruptly. The earphones are connected nevertheless. Then, I restart my blue tooth adapter and (after it lags a bit) they reconnect and work fine, but my keyboard doesn't and I need to remove it and reinstall it as a blue tooth device.

Dell has changed my motherboard twice and have formatted Windows once, but I still have this problem. (Note that in the past, after the first motherboard replacement, I am not sure if I did something as well, but this problem was gone).

Any thoughts? Please help as I can't work normally and Dell is on the way to replace my whole laptop for this, while I am trying to avoid it. Thank  you!

P.S.: Of course I have performed all the driver updates that Dell offers.