The wifi company I was using recently went out of business and I had to choose between either AT&T or Comcast. I chose AT&T. I thought I ordered wifi. The box for the router came today and mr tried to set it up while I was at work. So....it came with a broadband cable and an Ethernet cable. My old-ish MacBook does not have an Ethernet port. I plugged the broadband cable in to the only (?) phone jack in the apartment. Now when I try to use the internet, the router’s wifi signal shows strong on the list of available networks, but, when I try to open a page I get a message that says “trying to connect your broadband service “ or “broadband service not available”

Did I order the wrong plan, or something?