@chobo2 

Smart Connect is only available and take effect on the main network.

If a device only supports the 2.4G network, the router won't suggest it to roam to the 5G. More importantly, whether or not to roam to the other network is decided by the client device itself, but not by the router.

@chobo2 

Sorry, there is currently no router supports smart connect in the Guest Network.

As you can see, the Guest Network can be configured with a different SSID from the main router, and it is separated from the main network. Smart Connect cannot distribute client devices to a guest network when they are connected to the main.