WiFi hub and Ethernet mix

I have three hub WiFi devices. I have one connected to my isp via Ethernet, I have one connected via WiFi. I have a third that is too far away to connect via WiFi so I have run a cat 6 Ethernet. I currently have it connected to the system via the output Ethernet port on the main. I get WiFi but devices around it won’t connect. How can I make this function?