create subnet for smart home devices on Orbi

I need assist to create a subnet for smart home devices on Orbi (both wired and wife devices such as Roku, Harmony Hub, Echo) that is different from the subnet that we use for phones and PCs. I read the manual, could not find this topic addressed. I created a Guest wifi SSID and have some devices on it, and would like to be have some wired devices (via Orbi physical ports) and those on the Guest wifi to be on one subnet, and phones and PCs on a non-Guest subnet.