Aqara Door and Window Sensor P2 didn't join my Thread network

[JohnD]

Did you scan the QR code on the device when adding it to HomeKit?
The second time, you must use Multi-Admin, which will generate a different code.

Here’s how it works:

@JohnD

Matter Pairing of Devices

Initial Pairing (Onboarding)

1. Open the app of your choice (e.g., Apple Home or Aqara Home) to integrate the device into the respective ecosystem and scan the Matter QR Code found on the device or in the manual.
2. Your smartphone usually connects to the device via Bluetooth to exchange initial data.
3. The app passes the access credentials for your network (Wi-Fi or Thread) to the device. The device connects and is now part of your Smart Home.

Connecting to Additional Systems (Multi-Admin)

1. Generate Code: Go to the app with which you connected the device first (e.g., Aqara Home). Important: Do not use the sticker on the device for this second step.
2. Activate Mode: Look in the device settings for an option like “Matter Pairing Code” (Aqara) or “Turn On Pairing Mode” (Apple).
3. Copy Code: The app will now generate a new, digital QR code (or a numeric code). The code is usually in the format 0000-000-0000. When copying, ensure the format is correct (some apps require the hyphens, some do not).
4. Second Pairing: Now open the second app (e.g., Alexa or Home Assistant) and scan this QR code (or paste the numeric code). Important: Pairing should be done immediately, as the generated code is time-limited (usually 15 minutes).