Each Circle device comes with an included Ethernet cable that you can use to connect Circle directly to your router. You'll see the Ethernet port on the device by pulling up on the tab underneath the power port.
We recommend using the Ethernet cord after setup is complete and not before. Rarely, plugging Circle in via the Ethernet cable before setup is complete can cause some issues. Once you've created all your profiles, go ahead and plug that thing in! You'll want to make sure that it's plugged into your router's LAN ports and not the WAN port, or a switch.
Should I plug it in?
For most networks, plugging Circle in via Ethernet cable to your router should work great. It's the clearest connection Circle can have to your router and should help with speed or communication issues. But if you run into any trouble after plugging in the Ethernet cord, it's fine to unplug it. Just keep your Circle unit close to your router, we recommend setting it up 3-5 feet away. Any closer and it might be in a deadzone.