Due to the way the Bitdefender Box device enforces security protocols it is incompatible for use with the Circle device.
The Circle device uses ARP spoofing to identify and manage devices on the network. The Bitdefender Box device will detect this and keep the Circle device from working on the network. This is a feature on the Bitdefender Box device that can not be disabled to allow Circle to function.
There is not a work around for this device at this time. For use of the Circle device at home, we suggest replacing the Bitdefender Box with a compatible router.