Security Settings → Firewall Settings → Open Firewall → Filter MAC Addresses. You can set rules to strictly allow MAC addresses in the list to surf the Internet or prohibit computers in the MAC address list from surfing the Internet. If they belong to the same workgroup, you can enter "nbtstat -a computer name" at the CMD command line to get the MAC address, or go to the local ipconfig /all to get the MAC address of the controlled computer, and fill it in the router's "MAC address filter"-&add a new entry, and it's OK.