hello @Tôm    To block a device from accessing the GR12, you go to Home, select the device you want to block from Unique devices. On the Device-Status page, select Settings   It will also work from Devices showing under Hardware -> GR12     Unfortunately the device you want to block needs to be on the list. Not sure how to add only a MAC-address.   You might want to create a new WLAN with new SSID and password and make the corrupted WLAN a Guest network. It will give internet access but keeps people from getting on your LAN. People can get a new device and then blocking is not effective enough to keep them out.   Sadly you can not give MAC based access only block devices from accessing.   cheers   ... View more