Changing your ISP probably means you got a new router with a different Wifi network and password that your thermostat doesn’t know yet, which is why the app has stopped being able to communicate with your thermostat. Not to worry!
The simplest thing to do if you’re comfortable changing the router settings, is to simply change the network name and password to whatever they were previously. Your thermostat should then reconnect to Wifi and you should be able to control it using the app to change the thermostat PIN.
If you’re not comfortable doing that or the app still doesn’t work, you'll need to factory reset the thermostat using a computer.
- Connect the Nest Thermostat display via USB to a computer.
- Verify that the Nest Thermostat mounts (appears as an attached drive icon).
- If the Nest drive will not mount: Restart the thermostat and the computer.
- If the Nest drive still won't mount: Connect another device to the cable to see if it appears as an installed device.
- If it doesn't appear, use a different cable/port/computer.
If the Nest drive is successfully showing up on your computer, can you see a technicalinfo.PLIST file? If you get this far let me know and I'll ask a community specialist to assist with next steps, as these can't be shared publicly in the community.
