MAC Cloning is setting the MAC address of your PC or any other MAC address as your device WAN port and this is one of the methods to fix connectivity issues. MAC stands for Media Access Control and this is the hardware address that the Network Interface Card is manufactured with. At times computers face connectivity issues even with the hardware and ssoftwarefunctioning properly and at these times MAC cloning is used to fix this. An IP address is assigned to any computer by DHCP after reading its MAC address and thus IP address is lost once the computer disconnects. On reconnecting within the leasing period DHCP checks the MAC address again to assign the same IP address as before. Adding a different device such as a router that has its own MAC address connectivity issues with arise. 

These connectivity issues that arise due to the addition of external new MAC address into the network are fixed by MAC cloning. By simply cloning the MAC address that the ISP has used for assigning IP addresses this connectivity issue can be solved.