Thanks for posting and sorry for the delayed response. E294 means that your Nest thermostat is not recognizing the R wire. By any chance, is this a first time setup? If it is, have you checked on our online compatibility checker if your system is compatible with our Nest thermostat? If yes, please try the suggested troubleshooting guide on this link: https://bit.ly/3qjt7Si
Let me know how it goes.