I was trying in vain to add some Matter over Thread (and also Matter over Wi-FI) devices to SmartThings. To simplify: I was adding an IKEA ALPSTUGA CO2 sensor and an IKEA BILRESA dual button controller. I tried adding with multiple (three) Android phones running SmartThings (latest versions of software), and with one iPhone running SmartThings (iOS 18.5, latest SmartThings).
This evening, the Android phones failed at “Connecting to Device…[Matter]”, never actually making a connection with the device. However, when I started up the Matter over Thread devices, the Android phones / SmartThings did, in fact, detect that a new device was around and prompted me to scan the Matter QR code.
On iOS, I got to the OS “Add an Accessory” prompt, and some “Setting Up…” was happening. I also saw SmartThings prompt: “To connect to ALPSTUGA air quality monitor, you need to add it to iCloud. The SmartThings setup process will start after you add the device to iCloud.” However, the OS Matter sequence failed with the prompt: “Unable to Add Accessory / Home couldn’t connect to this accessory.” Ultimately, the SmartThings app reported: “Something went wrong / There was a problem adding this Device to iCloud. Try again. / Error code: 39-900”
What does all of this mean?
I should point out that very similar things were happening to me trying to add LIFX lights (Matter over Wi-Fi) to SmartThings on Thursday night. After many slow fits, starts, and restarts, Android wouldn’t work but iOS got working. However, the iOS onboarding process was very, very slow. On Friday night, I had one fail on iOS and then I switched to an Android phone, and everything was smooth like butter. I added probably two dozen LIFX Matter over Wi-Fi lights/switches, and two IKEA BILRESAs (Matter over Thread).
What is going wrong, and how can I get onboarding to work consistently?
When I plugged the ALPSTUGA in I got a notification on my Android that a Matter device had been detected. I went through the setup process and my phone wanted to use Google Home to set the device up and didn’t give me any other thread router options. I specifically chose to use another app, and selected SmartThings. The setup continued, and I got an error.
My phone certainly doesn’t support thread, so I don’t know how it knew there was a new thread device. IIRC, Matter spec includes a Bluetooth advertisement?
Then I went to Smartthings app, and went through the setup again. ST didn’t see the device at all, so I forced it into pairing mode using the circle button on the bottom. It instantly paired. This is a bit weird because it was obviously in pairing mode for my phone to detect it and, according to IKEA docs, it should be in pairing mode for first 15 minutes after being plugged in.
I get a categorized Air Quality Level (“Good”) but no CO2 or temp/humidity, which is why I ended up searching for the Alpstuga in these forums. I’ve seen a screenshot of someone who paired it with Home Assistant and got all the metrics, so those individual sensors are properly supported by Matter… just not ST?