Bose headphones volume controller not working with the iPhone SE 2020
I purchased the adaptor that combines lightning port and 3.5mm headphones port in one, to connect to my new iPhone SE 2020.
The volume controller on Bose headphones is unusable: I cannot adjust volume with it, when earphones jack is plugged to the iPhone through the adapter. The only way to adjust the volume is to use the iPhone's volume controller.
If I use the Apple earphones, connected directly to the device, I can use the headphones' volume controller with no problem.
Does it mean that the adapter is defective, or something else?
Thank you