Unable to mirror screen from iPhone onto MacBook

I have enabled AirPlay Receiver; I even allowed everyone on the same network to connect, disabled password, etc. Still, I get "Unable to connect to" the Macbook. (If I only allow the same user to connect, the Macbook won't even show on iPhone's display list.)

Just so people don't waste their time, I have also restarted both devices. (macOS 15.6, iOS 18.6.1)