Verizon FiOS → eero and fios

have had fios (symmetrical 1 g) for years and have had no trouble at all.
flummoxed installing eero and fios.

mixed system: iphones, macbook pros, windows 10 (mostly without wifi thus wired) with two wired printers.

need to keep two networks: fios and eero legacy stuff on fios, newer on eero wifi.

first turned off wifi on fios: LOST my wired setup printers and wired legacy devices.
then turned on wifi on fios and left eero wifi on.

have both networks. seems to work.
is this wrong headed and a beachhead for trouble???

any help would be great.
thank you.

Turning off the FIOS WiFi should not lose anything. It tells me that printers and wired legacy devices are connected using FIOS WiFi.

Eero should be conected to the LAN interface on the FIOS and not acting as an Access point extension or a bridge.