@russel0531 EAP won't change device IP, it's running on layer 2 data link layer.

If there is no Internet, you should check the connection between EAP and the main router. All network comes from your router.

About IP address, I'm not sure what's you mean "network IP" but the mobile phone should obtain private IP from the router automatically. And if this IP changed, you may check if your mobile phone enabled "random MAC address" so everytime it connects the wifi, it shows up like a "new" device for the router.