My B315 modem displays WAN mac addresses but not addresses for devices connected by cable (LAN) The reason I would like to know is that an unknown device was connected to the WAN for 264 hours continuous and I would like to go through a process of elimination to identify this unknown device
I also have a device which is connected via cable but shows up on the WAN list
If you navigate the router homepage, be it 192.168.1.1 or some other address, and (I've not used it or even seen it) look for the staus page. If it has it, navigate to the DCHP tab, showing all connected devices and hopefully their names. Check off all connected devices against the WAN page and you should narrow down your culprit.