In a home with a structured wiring cabinet, wired ethernet and multiple Eero's, you need to have your setup as follows to get the best performance and take advantage of the wired 'backhaul' feature of the Eero's.

I don't know if you have DSL, Cable or Fiber coming into your home.  The example below will assume its a cable based service provider.

INSIDE YOUR STRUCTURED WIRING CABINET:

    [ISP Cable Service Line] --> [Cable Modem] --> [Eero Pro 6] --> [1Gbit Ethernet UNMANAGED Switch]

    Then connect your home ethernet wiring to the above Ethernet Switch

    If your cable modem has more than one ethernet port in it, I would not recommend connecting anything to the 2nd port - but just use one connection from the cable modem to your Eero.  That Eero then serves as the router for the entire network in the home - both wired and wireless.

IN THE REST OF THE HOME:

    Now position 1 or more Additional Eero hubs in different locations of the home to get the best spread of wireless into different areas.  If you have a wired ethernet wall jack in a room, then you can connect additional Eero's to that connection to ensure you have full bandwidth from the switch in the cabinet all the way up to that secondary Eero hub.  

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