Ubuntu 20.04 as Bluetooth Speaker (A2DP sink) - volume control broken

I have been able to pair my iPhone SE (iOS 14.4.2) with my Ubuntu Desktop (20.04) using the default bluetooth settings application and I can play music and this is great but controlling the volume from iOS is not working. When I bring the volume all the way down to silent/mute the Ubuntu Desktop does mute its output but all volume levels above zero result with 100% volume.

Solution 1:

I solved my issue using modifications to the SystemD Bluetooth service proposed by this answer on a related question. Specific to Ubuntu 20.04 the SystemD service file has a different path.

Open this file as root: /etc/systemd/system/bluetooth.target.wants/bluetooth.service

Change this line: ExecStart=/usr/lib/bluetooth/bluetoothd

To this: ExecStart=/usr/lib/bluetooth/bluetoothd --plugin=a2dp

Then run these two commands:

sudo systemctl daemon-reload  
sudo systemctl restart bluetooth