Have you updated the Wifi information for them?
If you've already changed to a different Wi-Fi network, try these steps:
Instead of factory resetting your speaker or display, if you're comfortable changing your router settings, you can change your new Wi-Fi network name and password in your router's settings to be the same as the previous ones. Your device should then automatically connect to the Wi-Fi.
Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need assistance, feel free to start a new thread in the community and we’ll be happy to help.
By the way, thanks to @David_K for helping here!