If you find someone using your Wi-Fi network secretly without your knowledge, you could stop them. This is where the MAC address is useful. MAC address is the physical address of the network adapter of a device connected to the network. You can access the MAC filtering option of the router and block the device from using the network. For that, you need to know the MAC Address of the device. The following steps would help you to know how to block MAC address in Dlink router.