Engineer
Regular Contributor
Not sure I fully understand what you are seeing....on my modem, under Known CPE MAC addresses, it says 'Max 1' and contains the MAC of the attached router which is normal (and why it's sometimes necessary to shutdown your modem for a while to reset things at the ISP when changing routers).
Mine says max 3 and normally lists 1 which is the WAN MAC address of the router. Today, it lists 2, the WAN MAC and the LAN MAC of the router. Not sure why the LAN MAC is out there to the modem (across the WAN interface).