Why do I have to re-enter my Wi-Fi credentials on all my devices?

Re-entering the Wi-Fi credentials ensures that you are recognized on the new Wi-Fi network and are able to take advantage of its features.
Some Wi-Fi network broadcast names were delineated with 5 GHz or 2 GHz at the end.
Your devices will not recognize the previous stored credentials as they will appear different by the change in text of the network broadcast name.
This is most likely to occur if you previously used a Wi-Fi extender, Home Hub 3000, or third party solution, and want to continue using the same network name and password.