@yves_b they show as Ethernet. I guess the "Wifi" status when the S4 is wired to the ISP router instead of to the other wired unit (M4R) may be normal, as if it is saying "this unit is communicating...

@yves_b thanks for replying. No, when I put it in router mode and connect the M4R and the S4 in series instead of both to the ISP router, then the S4 shows as Ethernet:

Hello. I have Internet connection from AT&T at 1 Gbps, coming in a modem/router model BGW-320. I live in a two-story home of about 3400 sqft. Using only the wifi from the main router I can get wifi...