Thermostat displays E17 and cannot join a smart home platform (e.g., HomeKit, Alexa) even though Wi‑Fi works.

Safety first: No high-voltage work is required.

Steps to resolve:

• Update firmware: In the Mysa app, check for and install any available firmware updates.
• Reset integration: Remove the thermostat from the smart home platform (e.g., delete from Home app), then in the Mysa app, disable and re-enable the integration.
• Check router settings: Ensure multicast, mDNS/Bonjour, and UPnP (if required) are enabled on your router.
• Factory reset: If E17 persists, perform a factory reset on the thermostat and re-add it to both Mysa and the smart home platform.

If all network and firmware steps fail and E17 remains, the integration stack on the main board may be corrupted. Replacement may be necessary.