Whilst Hassan's suggestion did not fully solve my issue, it set me on the path that did solve it.
I don't have rep to post a comment yet, but just wanted to say thank you SO much to Hassan as part of your solution lead me to find a solution for this issue.
It was specifically installing Blueman that helped me solve my issue (whereby my BT headphones stopped connecting after months of working fine).
Whilst Blueman did not solve my issue, it did provide the error:
Connection Failed: blueman.bluez.errors.DBusFailedError: Protocol not available...
On Googling that error, I then did the following and the headphones now connect.
I installed blueman
:
sudo apt-get install blueman
Then I ran these commands:
sudo apt-get install pulseaudio-module-bluetooth
killall pulseaudio
Then, after restarting Ubuntu, I was able to connect via Blueman.
lspci -knn | grep Net -A3; lsusb; rfkill list
terminal command.