Bluetooth issues on Mint 19.3. Kernel related or some hardware failure?

I have annoying issues with bluetooth on my desktop running Mint 19.3 (fully up to date). Basically, it is totally unreliable.

• Devices will disconnect on their own
• Devices will not connect
• Bluetooth management applications (like blueman) will freeze
• Application playback will switch sound output devices
• Etc....

Another annoying issue is with youtube. Youtube playback works perfectly, then all of a sudden stops (spinning wheel) then sound jumps from headphones to the speakers. The bluetooth connection is then lost.

The only workaround I found so far (taken from Ubuntu forums) is to:

• sudo modprobe -r btusb
• sudo modprobe btusb
• shutdown headphones
• Kill blueman
• Restart headphones
• Reconnect

Sometimes, it takes 4 or 5 attempts.....

I have been using the same bluetooth hardware (USB dongle and same 2 pairs of headphones) for at least 2 years on this desktop and never had an issue. I have been waiting for a kernel upgrade but clearly, it has not helped.

Back when it started, I switched from whatever bluetooth manager ships with Mint, to "blueman". It helped but still very far from functional.

I often see these messages in blueman:

Code:Connection Failed: blueman.bluez.errors.DBusInProgressError: In Progress...Code:Connection Failed: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.I use an ASUS bluetooth USB dongle. Headphones and dongle all work 100% on other non-linux devices so I know they are not failing.

When such issues occur, "dmesg" yields:

Code:[405377.737402] Bluetooth: hci0: command 0x1405 tx timeout
[405379.753404] Bluetooth: hci0: command 0x1403 tx timeout
[405381.769404] Bluetooth: hci0: command 0x0c2d tx timeout
[405383.785392] Bluetooth: hci0: command 0x1405 tx timeout
[405385.801374] Bluetooth: hci0: command 0x1403 tx timeout
[405387.817371] Bluetooth: hci0: command 0x0c2d tx timeout
[405389.833373] Bluetooth: hci0: command 0x1405 tx timeout
[405391.849376] Bluetooth: hci0: command 0x1403 tx timeout
[405393.865382] Bluetooth: hci0: command 0x0c2d tx timeout
[405395.881370] Bluetooth: hci0: command 0x1405 tx timeout
[405397.897387] Bluetooth: hci0: command 0x1403 tx timeout
[405399.070533] usbcore: deregistering interface driver btusb
[405403.942671] usbcore: registered new interface driver btusb
[405404.149417] Bluetooth: hci0: BCM: chip id 63
[405404.151417] Bluetooth: hci0: BCM: features 0x07
[405404.168429] Bluetooth: hci0: workstation
[405404.170417] Bluetooth: hci0: BCM20702A1 (001.002.014) build 0000
[405404.174460] bluetooth hci0: Direct firmware load for brcm/BCM20702A1-0b05-17cb.hcd failed with error -2
[405404.174465] Bluetooth: hci0: BCM: Patch brcm/BCM20702A1-0b05-17cb.hcd not found
[418866.136604] usb 7-3: reset full-speed USB device number 2 using ohci-pci
[418927.179153] Bluetooth: hci0: command 0x0406 tx timeoutI am pretty sure its kernel (or module) related based on the searches I've done, but no apparent solution seems to exists... What next?