How to make smart home with arduino and ethernet?

Hello everyone.

I'm studying university last year.I design a smart home as project. I used arduino and w5100 ethernet module. However, I have any trouble. My teacher said "You should find a modem. Then you must use this mode as router. Also you should open wireless local area network. Then you can do controlled with project." But I dont understand him. I opened wireless local area network. Then I noted the ipv4 adress However, I dont know where need to use it. Do I need to write while programming arduino? I mean, Where am I do the ıpv4 adress and wireless local area network.