Internet

My power went out recently, it came back and I tried reconnecting my Laptop and cell phone to the internet but I came across a problem. My network showed up and was asked to enter my password but I didn't get any internet access, for example, my laptop said that my Wi-Fi connection was secure but I had no Internet connection. I went to check my router and the following lights were solid/flashing green: Power, Broadband 1, and Wi-Fi. The 'Service' light started out green but after watching it for a while it then turned red and the light turned off. I followed the instructions on the myAT&T app but one of the instructions I had for this was "Ensure there is a cable plugged into the green port on your AT&T Residential Gateway and it is securely plugged into the wall jack" as well as "Ensure that the AT&T Residential Gateway is securely plugged into an electrical outlet."  The problem is I did not have a cable connected to this port on the router before the power went out, and my internet worked before. Should I just go ahead and make an appointment for someone to come to my home? or is it something that I can fix by myself? Any help is appreciated, Thank you.