Can't establish connection between Unity and Ouest 2 in play mode

I unfortunately can't get the Oculus Quest 2 to run in Unity's play mode.

My system info:

• OS: Win10

• CPU: i7

• RAM: 16 GB

• GPU: RTX 3060 Laptop (driver version 516.59)

• Unity version: 2021.3.8.f1 (older versions do not work either)

• XR Plugin Management: 4.2.1, Windows Settings: Init XR on Startup checked, Plug-in Providers Oculus checked

• Quest 2 system version: 37314400808900000

• USB debugging allowed

• Oculus Link active (connected via USB 3.0 cable)

When I enter play mode the following warning appears: "Unable to start Oculus XR Plugin."

What I have tried so far:

• Ouest 2 reset to factory settings

• Reinstalled Oculus environment and drivers

• Unity reinstalled

Unfortunately, all without success. But I would rule out a hardware problem, because with Unreal 4.27 a preview in the editor works fine. What do I miss?