Hello Arthur2,
Thanks for reaching out. Having the Nest Thermostat show offline is never ideal. Let's jump in and get you back online.
I did come across a useful article with some methods for troubleshooting your Nest thermostat when it is offline. Please let me know whether it resolves the problem or if it remains, so we may look into more potential solutions. If it does, tell us which Nest Thermostat you have and gather its power readings in the Technical Info settings or in the Equipment settings, depending on your thermostat version.
Keep us posted.
Best regards,
Mark
