Not listing all connected devices? (VMG3925-B10B)

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Is it just me or is the connection status screen very incomplete?

I know I have routers connected by wire to this (main) router, they don't show up.  Would I not see them as they're just being used as WiFi boosters and are therefore set up as "WiFi routers".  Seems to me they're still connected by wire to this router so why wouldn't it show them?

Is there a way to get a more complete list?  The ARP table seems just as sparse.

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