It’s a screenshot from a Tomato flavor of router firmware.
Not really important, but br0 represents the wired network the Form 2 and Form 3 are plugged into, and eth1 represents the particular wifi interface the Form 3L is connected to (which in turn is also bridged to br0). wfilter is just a hotlink that (presumably) lets you quickly add the MAC address to a filter (to prevent or permit wifi access).
I might have asked my question prematurely. I should probably try plugging the 3L into a hardwired connection first to see if the behavior changes. I did see the correct machine name for the 3L very briefly, I think it was just after a router reboot. The 2.4GHz interface on my router actually started acting up shortly after doing this troubleshooting so it’s also possible something funny is going on there.