go to xfinity.com/authorize to continue the xfinity activation process. and Enter code to activate modem. To activate an Xfinity Gateway. Let's activate xfinity device. Visit xfinity.com/authorize from another device such as a mobile phone, tablet, or desktop. From the web browser, enter the six-digit Xfinity.com/authorize code provided to the Roku device. And stream your favorite shows and movies anytime, anywhere with Xfinity Stream. Watch TV series and top rated movies live by authorizing or certifying Xfinity TV.