Are you a new ADSL or ADSL changing to NBN or a new NBN user?
If NBN, do you know what variety of NBN?
So, you're saying that your laptop is connected to router by cable and it can access the internet, Google for example?
Then, "the wifi connects but the server doesn't respond"? In your device's settings (phone/tablet), does it show a connection to the wifi router with good signal strength? Is the wifi on your laptop disabled at this point? I can't recall there being anything extra to do once the device has a connection.
If you need to reconfigure the wifi router, best done using your laptop when connected by cable. In the browser address bar, enter the ip address of the router and then logon to the router using its userid and password which might be found on a label on the router, unless you have changed it.