|If you use the setting on your router that says "allow only the devices with the following MAC addresses to connect to my network" for this then yes. Even if someone knew the wireless encryption key, they wouldn't be able to connect a device to your WLAN that didn't have one of the MAC addresses you specified in that list. |
It's an added layer of security that may or may not be of value to you. It prevents anybody from attaching new devices to the network without your allowing it. Only you can determine if this level of security is of value to you.
As to how you do it, the manual should explain it.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.