Your Internet service provider might have provided you with a modem/router combo for your house. You may have also connected a second router to this as an Access Point or as a totally separate router to put off its own Wi-Fi network.
The Circle device will only manage one network at a time. Make sure that the Circle device is paired with whichever router the devices you want managed are also connected to. Below we've listed the ways that two routers can be setup on your network and how to best connect your Circle device to them.
Bridging to your main router
Your Internet service provider or yourself might have setup your router/modem combo in bridge mode, and then connected your main router to it via an ethernet cord. In this scenario your router/modem combo won't be putting off its own Wi-Fi network so feel free to pair your Circle device with your main network. If you want, you can plug in your Circle device via ethernet afterwards to the router that is putting off Wi-Fi and not in bridge mode.
Router and access point
If you've got your router/modem combo setup as the DHCP server, and set the second router up in Access Point mode, connect the Circle device via ethernet to the router/modem combo after pairing and it will see all devices that connect to your network. If your router/modem combo is putting off a different SSID then the Access Point we recommend making them the same, or that the Circle device is paired with the Wi-Fi put off by the router/modem combo.
Two separate routers
Some households might have two routers setup, both with their own DHCP servers running on the router and putting off their own networks. This isn't a setup we recommend, but if that's how your house is set up, make sure your Circle device is paired with the WiFi network that you want to manage, that the devices you want to manage are connected only to that network, and that they don't switch over to the other network. (You can make sure devices stay on the right network by changing the second network's password, and only allowing the correct devices to connect to that second network.) If you're plugging the Circle device in via ethernet, make sure that it is connected to the router that the devices you want to manage are also connected to.
For more about advanced network setups and the Circle device, check out this help article.