MacBook Pro bluetooth not connecting properly

I have several devices that connect through BlueTooth and both my MacBook Pro (2015) with fully updated software and the BOSE SoundLink® Bluetooth® speaker III (bought at the Apple Store around the same time) have bluetooth issues.

My MacBook Pro:

• Sometimes will not connect at all to my Bose speaker, even though it will say it is "connected" and have the speaker's logo "lit up in blue" suggesting so.
• Sometimes it will connect initially, but then disconnect. When this happens, it cuts-off only once - after varying periods of time (the Bose speaker will apparently turn-off) - after which I will re-connect it and then it will play-on with no further issues until I turn it off.
• I've also tried using my girlfriend's SoundLink® Mini Bluetooth® speaker with my MacBook Pro, and have the same issue.
• I've tried every possible combination of turning on/off devices, turning on/off the bluetooths, turning-on the bluetooths in different order, etc; and have found no discernible pattern that may give me clues as to what's going on.
• It also has poor connection to my brand new AirPod Pros when on a call (Zoom, WhatsApp, Teams). The calls starts OK, but after a few minutes a lot of audio interference make the calls untenable. I then switch to my old Apple earphones (the white ones with the cable) and the calls are perfect. My AirPod Pros are brand new and have no issue with their new iPhone 13 Pro.

So, it seems my MacBook Pro is the common denominator of all the Bluetooth issues.

Any help will be most welcome!

Cheers from Amsterdam!

Max