I'm having the same problem. I registered my hardwired MAC address from my mag254 originally, now I want to change to use the WiFi MAC address so I don't have to be cabled to the wall. I can updated the existing (hard-wired) MAC address by changing the last digit by one, and it updates it. If I copy and paste, or type carefully in the new MAC address from the adapter it will not update to that value. I have confirmed the MAC address on 2 separate machines for this USB WiFi adapter (and it is printed right on the side of it) and confirmed in my existing router's DHCP table. When I check this MAC address using one of many MAC address validators online, it complains that it is not a valid MAC address...but it is for sure. I'm wondering if the papiao page is using some form of MAC address validation JavaScript (or other) that is not recognizing some of these new MAC addresses being issued now.