For a test, does a computer hardwired directly to the router / gateway device with an ethernet cable have the same problem ?
Guess if you are seeing that message when logging into the admin tool you are using Xfinity Pods.
They control your wifi network automatically.
If you want more control, stop using them. Use a different type of extender, or bridge the gateway, use your own router and again use some other type of extender or mesh device/s if required.