If you have a desktop computer that works on the Internet with a cable, but wireless devices don’t connect, then your problem is with the router.
Locate the power connector and pull out the cable, leave it out for a few seconds and plug it back in.
Your router will go through the motions of reconnecting to your ISP. Once you have green lights and everything has settled down, retry the Internet on wireless devices. It’s a simple fix but one that most people don’t think about.