The Circle device works to manage the traffic from a majority of extenders that are used in conjunction with your home router, and in most cases they are compatible with Circle. Check here to see if your extender has been marked as incompatible with the Circle device by our team. Otherwise, we recommend checking in the Circle app after setup for them in your list of devices, and setting them as "Unmanaged" if they appear.
Don't pair the Circle device with your extender
We do not recommend pairing the Circle device with an extender's Wi-Fi network if you have the option. If you have an extender on your network and are having issues setting your Circle device up, try powering off the extender temporarily until your Circle device is paired. Then plug your Circle device directly into your router using the provided ethernet cord and power on the extender. Definitely don't pair your Circle device with a Wi-Fi network that has the same name as your normal network but with an added "_EXT". That's the extenders network, and pairing to that will mean your Circle device can't see the rest of your network.
For more about advanced network setups and the Circle device, check out this help article.