I've solved by myself: the BT antenna was simply disconnected from the intel wireless board. That's it 
Hi guys, I have a very annoying problem with my new Dell XPS 15 9520. Since switching from my old Dell 7559, with the new 9520 (in the same desktop as my old 7559 was) I can't listen properly to music with 3 different pair of headphones, video or any audio output via Bluetooth. I have researched already online about it and there are various solutions which, sadly, didn't work at all for me. For example: - uninstalling Intel Bluetooth drive or upgrading it; - disabling RFCOOM: - disabling\enabling the Bluetooth in BIOS and even the fingerprint reader (some experienced BT-related issues); - go outside (in my garden) to exclude any interference; - disabling ALL possible connections (mouse, phone, WiFi, etc);   ...and I even briefly tried to connect my headphones to a LIVE USB of Ubuntu 22.10 to exclude any possible Windows-Driver related issue.   Yet, no result.   Any idea? I've ordered an extra Bluetooth USB adapter for when I'm home, but I'd still like to solve the problem with the native BT, and not recur to a "symptomatic solution"...   Thanks in advance!
XPS 15 9520 (2022) Bluetooth audio stuttering, not working properly, 
disconnecting