Some routers can enable a security feature that keeps devices on the network from spoofing their IP or MAC address. Typically, IP or MAC address spoofing is used to elude detection on a network. The Circle device's filtering and management uses similar practices to MAC address spoofing, so we don't recommend enabling MAC or IP spoofing checks on the network you want the Circle device to manage. If you think you've enabled this security feature on your router, log into the router and disable them. Check your router's manual for more information.
For more about advanced network setups and the Circle device, check out this help article.