I now have AT&T fiber optic using their modem/router in my house. Previously I had Comcast cable and used my Arris SBG8300 for WiFi. 

 I have a Cat5 cable running from my house to my detached garage which I used in the past plugged into my Arris Model SBG8300 (house) when I had Comcast Cable. The Cat5 cable was plugged into a laptop I used in the garage. My question is, can I plug my Arris into the Cat 5 cable in my garage, connected to my AT&T Router/Modem (house) and use it for Wi-Fi for some remote security cameras in my garage?