Lets start with some basic troubleshooting steps before getting in to changing fiewall settings.
Turn off computer, press the reset button on the back of the router then unplug the router, and unplug the cable modem.
Makes sure ethernet cable from cable modedm is plugged into the WAN port of the router.
Power on cable modem and give it a minute or two to fully boot up.
Power on router and give that a minute to boot up.
Turn on your computer and see if you get IP address from the router and if you can connect to Internet.