Hi there! Thanks for reaching out about the upstairs unit showing as offline on your Carrier Home app while the downstairs unit works fine. I want to help get that fixed for you.

To start, could you tell me if the upstairs thermostat itself is displaying any error or connectivity messages on its screen? Also, is the upstairs device still connected to your Wi-Fi router? Knowing that will help narrow down whether this is a network or device issue.

In the meantime, here’s a straightforward step-by-step you can try to troubleshoot this offline status for the upstairs unit:

1. Check Wi-Fi Connection on Upstairs Thermostat: Confirm that the upstairs thermostat is connected to the Wi-Fi network. Sometimes it may drop connection even if your phone is fine.

2. Restart the Upstairs Thermostat: Turn the thermostat off and then on again to reset its network connection.

3. Restart Your Wi-Fi Router: Sometimes routers can cause connection hick-ups. Restarting it can help.

4. Verify App Permission and Account: Make sure your app is logged in with the correct account and has permission to access both thermostats.

5. Check for App Updates: Make sure your Carrier Home app is up to date in the App Store.

6. Re-add the Upstairs Thermostat: If it’s still offline, you could try removing and re-adding the upstairs thermostat in the app.

If after this the issue persists, it could indicate something more specific like a mechanical or firmware issue with the thermostat itself. I can guide you through checking those next steps if needed.

Please let me know what you find after these steps or if you want me to walk you through them! Are you able to check the thermostat screen or Wi-Fi status right now?

Thermostat works

Thanks for confirming that the upstairs thermostat itself is working fine. Since the device works but shows as offline in the Carrier Home app on your iPhone (iOS version 26_2_1), it suggests the issue might be with the app or the network connection between the thermostat and the app.

Let’s try a few focused steps to troubleshoot the app’s connection to your upstairs unit:

1. Force Close and Restart the Carrier Home App:
Double tap the iPhone's home area to bring up the app switcher, then swipe the Carrier Home app off the screen to close it fully. Open it again and check if the upstairs unit shows online.

2. Check Wi-Fi Network Stability:
Confirm your phone and the upstairs thermostat are connected to the same Wi-Fi network and that the Wi-Fi is stable without intermittent drops.

3. Log Out and Log Back In:
Sometimes, the app session might glitch. Try logging out of your Carrier Home account in the app and logging back in to refresh the connection.

4. Update the Carrier Home App:
Ensure your Carrier Home app is the latest version from the App Store. An update may have fixes for connection issues.

5. Re-add the Upstairs Thermostat in the App:
If possible, remove the upstairs thermostat from the app and then add it back. This can re-establish the link and clear cached errors.

6. Restart Your iPhone:
A simple restart can refresh system processes that might affect app connectivity.

If these steps don’t help, it might be worth checking for thermostat firmware updates or contacting your local Carrier expert as sometimes device firmware mismatches cause app connectivity issues1 6.

Would you like me to guide you through any of these steps now?