@Rcf026 It is, indeed, a good idea to disable WiFi operation of the AT&T router. The AT&T router will continue acting as a router. It will probably not impact your usage of the network.

@Rcf026 Next time you upgrade the system, you can, indeed, keep the same SSID/password, and the clients will find it. Disabling the wifi on the modem will no stop the modem to act as a router....

@Rcf026 If everything works well, and if some devices are still using the old SSID, you can leave it running. The video shows how to create a new wifi network from the Deco. It would have been...

@Mike101 Given that all wifi channels are always available for the backhaul, I believe the logic of the app has been changed. In the past, it was possible to setup wifi 6 is "only for backhaul". Now,...

@Rcf026 I believe the main reason to disable the old SSID is to ensure that devices use the new SSID, because the new one offers a better coverage and transparent roaming. Something else: it is...

@NetworkNoob2 If the app does not allow controlling your Deco mesh, I believe resetting the Decos will be sufficient, and you will be able to create a new network in the app. via the "+" button.