Google home so no longer sees my thermostat

[LarryL2]

After using my Google Home app for some years with my Nest thermostat, now suddenly the app wants me to reconnect because it doesn’t see it on the network. 

[MplsCustomer]

@LarryL2 

Do you by any chance have an older thermostat?  The Nest Learning Thermostat (1st gen, 2011), Nest Learning Thermostat (2nd gen, 2012), or Nest Learning Thermostat (2nd gen, Europe version, 2014)?

If so, see this post about discontinued support:

https://www.googlenestcommunity.com/t5/Nest-Thermostats/Google-home-so-no-longer-sees-my-thermostat/...