I recently got xfinity internet/wifi. I set it up through the app on my phone very easily. My phone connected without a problem. When I look on my computer though for available wifi networks, the name of my network does not appear. I restarted both my gateway and my computer in an effort to fix this, but it did not work.
The two WiFi bands have recently been combined into one with the Comcast gateway devices.
If you are not using any Xfi Pods, you can try separating the 2.4 and the 5.0 bands and give them two different broadcast names / SSID's;