On your PC:
Settings > Audio > Networked Devices
First see if your iPhone is listed there.
If it is not, hit the refresh 'Circular Arrow"
If it still does not show, Contact Roon.
If it does show, this area allows you to select it as your default Output Device. I have Not Enabled my Google Pixel XL.
See how the remote works for you via the iPhone first (that is Do Not Enable it).
Try this approach first.
Settings > Audio > Networked Devices
First see if your iPhone is listed there.
If it is not, hit the refresh 'Circular Arrow"
If it still does not show, Contact Roon.
If it does show, this area allows you to select it as your default Output Device. I have Not Enabled my Google Pixel XL.
See how the remote works for you via the iPhone first (that is Do Not Enable it).
Try this approach first.

