I just had the same experience this week. Allegedly there was a batch of about 500 sold through Ace Hardware (where I got mine) that were not supposed to be sold. All of these came with the incorrect firmware and are not able to be updated remotely. They’re shipping me a new one so hopefully that sorts it out.
Update:
After seeing posts that Resideo is unable to remotely update X2S thermostats with version 01.00.01.00 firmware, I decided to go buy a second thermostat. I can confirm that v2.0 firmware is Matter enabled. The First Alert app DOES have a Matter menu option that generates a matter QR code/serial number which is scanned/entered into the Home Assistant Matter Server integration. Adding the thermostat to the Home Assistant Matter server is ridiculously easy. The default Home Assistant thermostat applet allows temperature adjustment and off/cool/heat mode control, but no fan control or humidity display. Digging deeper into the matter server, it doesn’t appear that the X2S supports relaying humidity measurements even though the X2S contains a humidistat and the Matter standard supports this function.
Overall, the X2S falls short of my hope for a local-only, internet-disconnected IOT product that respects your privacy. It’s clear that the X2S is designed as an internet-connected only device and that the marketing flourish around Matter was only used to draw in unsuspecting victims.
Additional Findings / Complaints:
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Setup: As stated before, setup requires the First Alert app and forces geolocation. Use of the app requires account creation, and forces users to provide their full name and email address. The First Alert app disables itself if location services are disabled and does not function without an Internet connection. Smart features of the X2S cannot be configured without the First Alert app.
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Firmware Update: Either Honeywell/Resideo do not plan on issuing firmware updates or they have intentionally omitted a firmware update function on their devices. While I’d prefer to interpret this as incompetence over intention, I have strong suspicion that the omission of this function is a power grab. Omitting the firmware update function requires users to stay connected to Resideo’s servers. This requires consumers to keep their devices exposed to the internet. More to the point, giving the user “too much control” over the device compromises the device’s ability to spy on its users.
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Firewall intervention needed: Once Matter is configured, the X2S continues with frequent connections with Resideo. Even after the thermostat has been deleted from the First Alert app, the thermostat continues to connect to provds.prod.granite.clouddevice.io. This is unacceptable as casual users would expect that the X2S ceases internet communication once they delete the X2S from the First Alert app.
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False Error Codes: Once the thermostat is added to Home Assistant and deleted from the First Alert app, the thermostat displays a caution icon and a No Wifi icon even though the thermostat is still connected with local wifi. The ALRT submenu will then perpetually display error code 388 - Register the thermostat online. When firewall settings are configured to block the thermostat from the Internet completely, error code 399 - No Internet Connection will be displayed. There is no way to reset or disable these messages.
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DNS Spamming: After blocking the thermostat from the internet, the thermostat spams DNS servers 2x per minute looking for provds.prod.granite.clouddevice.io. There is no way to disable this activity.
Hey there!
I know this is an old thread but in case you were having trouble adding your X2s I wanted to drop this little nugget in there…
I have a mesh network with 5 nodes in my house (Synology of various types). Couldn’t get the X2S to link up with Home Assistant no matter how hard I tried UNTIL I disabled IGMP snooping. Once I did that, everything worked! Steps were:
- Get the thermostat talking to the First Alert Resideo App
- Run the Resideo app, have it generate the matter QR code
- Home Assistant - add device - Matter Device (assumes you’ve already set up the hub) - Add New. Scan the QR code.
Hope this helps someone!
I unfortunately only discovered this thread after buying the thermostat. About to bring it back 
- Honeywell forces you to install their app simply to create the QR-code which is only valid for 15 minutes.
- No chance to get the device into pairing mode without the app
- Their app needs quite some permission, most not really needed for a smart thermostat
- As mentioned above one needs to block access to not only http://provds.prod.granite.clouddevice.io/ in either dns or firewall but pretty much to *.clouddevice.io and tabasco-prod.azure-devices.net
I will give it a few days because I really like the idea of a matter based thermostat
I also had many problems with pairing. I am running HA in a docker container on a raspberry PI. I had to turn off tailscale vpn before it would pair. Hopefully this will save someone the many hours I spent trying to get this to work.