Unfortunately, using a browser didn't help - I still get errors. If anyone has spoken to Google support have they had any suggestions or do they have access to any kind of logging so we can see what's failing?
I suppose I could reset all of my devices to factory and then create a new account but that sounds like a nightmare.
Thanks for reaching out.
We're sorry to hear that you're experiencing this with your devices. Kindly check these steps and see if it works.
Important: If you started using the Nest app after August 19, 2019, you’re already using a Google Account and don’t need to migrate.
If you started using the Nest app before August 19, 2019, you created a Nest Account to manage your Nest products. You now have the option to migrate your Nest Account to a Google Account, creating one unified Google Account that you can use to manage products and homes in both the Nest and Google Home apps.
If you migrate, your Nest data will be associated with your Google Account. To understand how Google will use your Nest data if you migrate and how you can manage your Google settings, read our Privacy FAQs.
Note: If you use a Gmail address to sign in to your Nest Account, you might still need to migrate.
If you migrate your Nest Account to a Google Account, your experience of your Nest home and products will change. Migration is optional, and once completed, is not reversible, so it’s important to understand the changes that migration will bring before you start.
Here are some key things that will happen when you migrate:
We recommend that you read all the information in the Important changes when you migrate and Privacy and Terms of Service sections to help decide if migration is right for you at this time.
How to migrate
You can only link one Google Account to one Nest Account.
Let us know how it goes.
Thanks for letting us know about this. Glad to know that all devices are working now.
Since this has been resolved, we'll consider this complete and will lock the thread in 24 hours. Feel free to start a new one if you need assistance with your Google Nest devices and the Community would gladly lend a hand.