Weird MAC Address Issue

I have found the MAC on my wiser, which is the same as the MAC listed for the IP doing an arp on the network, is different to the MAC on the status page for my Wiser.
the only difference is the last digit in the MAC "9" which is appearing as a letter A on the status page instead.

I found this while trying to sort out my static ip's for my fixed gear in the DHCP server of my router.

Incidently I also wasted 2 hours trying to find out why my Wiser had stopped working - for future reference if using set up "B" (using existing ADSL router and switches) make sure Wiser and LAN is connected on a lan port and not the WAN bridge

Interestingly as long as my IPhone swapped AP's (it maintained the IP address) from the main AP to the Wisers AP I could access the Wiser screen.

 

I am guessing the A is the LAN mac address and the 9 is the WAN mac address. A comes after 9 in hexadecimal. Which MAC address is being used to respond to an ARP request will reflect which interface the request came from. For example, on mine wifi and lan are ...:8B while WAN is ...:8C. If I try to arp-ping with only the LAN connected, then I get :8B response. If I arp-ping with the WAN connected, then I get :8C.