I'm sorry to hear your having trouble with your Nest devices being stuck on one Wi-Fi. Let's check it out. What Nest devices do you have? Is there a change on your Wi-Fi and you're trying to connect your Nest speakers to a new one? If that's the case, follow the steps below:
If your speaker or display isn’t connected to a Wi-Fi network, set up your speaker or display on the new Wi-Fi network:
If your speaker or display is connected to an existing Wi-Fi network, but you'd like to connect it to a new one, follow the steps below:
If you get an error message that says "could not communicate with your [device]" when you try to forget your network, or the steps above don't work, you'll need to factory reset your device and set it up again.
Tell us how it goes.