Your phone is the racket. Pair it once, then swing. No server is involved at any point, including this pairing.
Use the camera app. It opens the racket page — same Wi‑Fi as this laptop.
The phone will display a second code. Hold it up to this laptop’s camera.
Two codes because an introduction goes both ways, and a QR only points one way. The way round that is a server in the middle, which this deliberately does not have.
Practise the timing while you wait: press Space or click the court.