Jeff C. cMoo92 , Thanks both of you. Just to be absolutely certain I am understanding, you are saying that the ethernet ports on any eero will be bridged to the LAN? (both mesh and original wired LAN. Of course, excluding the "WAN" port on a NATed eero, of course.) That other than the "WAN" port of an NATed eero, all the ethernet ports on all the eero can be used as a giant 24-port switch? (Assuming I bought that many eero, of course. 😉)

So in the following pics, where there are 3 eero in a mesh, I can print from the PC (connected to eero 2 ethernet port) to the network printer (connected to eero 3 ethernet port.) eero 2 & 3 in both pics are NOT the ones with the wired route to the modem.

If these scenarios work, that is exactly the answer I am looking for.   Jeff C. , at the moment, we have kept the original router because we needed the additional ethernet ports. So the eero attached to the router is bridged. I would love to have the eero doing the NAT instead, but when I did this installation at a client's home, I found out that several vendors had added on many additional devices to the various bridged access points that I was unaware of. So eero, with only 2 ethernet ports, became a hassle in this instance and I had to spend several hours figuring out each vendor's setup and what I could move around. In particular, the client's solar panels are using a power line adapter for ethernet, which appears to be unreliable as the client seems to need to reset the power line adapters regularly. And the power line adapters don't like the RFI filters that the client has in most of their power strips. So if I can add one more eero to become a "receiver" for the solar panel, that will help simplify this client's setup.  (In other words, in the above pics, replace the network printer with the solar panel controller.)

Otherwise, eero at this location has been great! The original construction is complex and unusual, as there's a lot of metal and reinforced concrete in the walls. So adding ethernet wires is extremely difficult and Wi-Fi with traditional access points has been disappointing. With eero I can build a mesh route through the stairwells. There are still a couple of weak spots so a few more eero may be needed in the future. (Currently have 6 at this location 😳) So this "receiver" solution would be a great news for this client.

Thanks again!

Thank you very much! Have a great day! 😁