Have wireless signal but no IP

Starting from the obvious, check that the cables are installed correctly.
You have to have a cable that brings the internet to your place.
Connect that cable into the router's jack labeled Connection to Modem.
Then get another network cable and plug it into any other jack form the back of your wireless router, and the other end into your laptop, just to make sure you are getting connected.
Once you are sure you can surf the net, unplug the wire from your laptop, and you should be able to surf wirelessly.

And if you still can't connect, let me know to perform additional steps.

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