Once I disable wpa_supplicant the device is still reachable

Hello,

I have a device, wired connected to a router that I use to certificate (8021x) the devices connected on that particular subnet.
Once I enable the wpa_supplicant the router correctly recognizes the certificates and "admit" the device to the subnet.
I have access to the device and I can ping it.
Once I disable the wpa_supplicant (using wpa_cli terminate) the device is still reachable.
What I would like to happen is that once I disable the wpa_supplicant the device will be removed from the subnet.
I also try to add

ip link set ethX down ; ip link set ethX up
or
ifconfig ethX down ; ifconfig ethX up
or
ifdown ethX ; ifup ethX

after terminate wpa_supplicant but as soon as the network is back on, the device is stil pingable even if no more wpa_supplicant process is running

If I reboot the device, after restarting the device is off the subnet (until I start againg the wpa_supplicant service)

Any suggestion?

Thanks