Requirements: Wi-Fi network, Mobile hotspot.
Check the password to your Wi-Fi network – The password may contain letters/special characters (= , _) that the thermostat can't support. Change the password to your Wi-Fi network so it only contains common letters or numbers.
The password for your mobile hotspot, might also contain letters/special characters (= , _) that the thermostat can't support. Try changing the name of your Wi-Fi network so it only contains common letters or numbers.