@DocMarty ,

Overall, if you have the opportunity to switch our Range Extenders for a Full Mesh system, you should switch to mesh. REs have a few unique properties due to how they repeat wireless signals that can result in a dramatic falloff in performance. It is also not really recommended to add more than one range extender in close proximity since they can potentially confuse devices and have been known to cause problems with the connection of some IoT devices.

One thing to consider is that the Deco Mesh can operate as the router for your network, so you would actually need to disable the wireless functionality on the Xfinity Gateway, otherwise, they would need to be used in AP mode (which would still most likely result in an increase in performance).

Lastly, a Mesh system is far more flexible in how it is used and connected, so if your needs change or you find you need to add access in a unique area, you will likely have an easier time with a comprehensive mesh network when it comes to upgrading or adjusting your setup for your needs. Your mileage will, however, vary depending on what model Deco you choose.