Unable to connect to 2.4ghz wifi

The two WiFi bands SSID's have recently been combined into one with the Comcast gateway devices. Some devices get confused and don't know how to see / talk to combined SSID's.

If you are not using any Xfi Pods, you can try separating the 2.4 and the 5.0 names and give them two different broadcast names / SSID's;

https://www.xfinity.com/support/articles/change-wifi-mode-admin-tool-xfinity-xfi 

Associate the devices with the new / respective 2.4 or 5.0 SSID (broadcast names) and password.

Hello and thank you for taking the time to reach out to us here on our Xfinity Forums. I definitely understand how important it is to stay connected, especially for home security! I would be more than happy to take a look and assist with finding a resolution. Please send us a direct message to "Xfinity Support" with your full name and address to get started.

To send a direct message you may need to:
Click "Sign In"
Click the "direct message" icon
Click the "New message" (pencil and paper) icon
Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list which appears. The "Xfinity Support" graphic replaces the "To:" line
Type your message in the text area near the bottom of the window
Press Enter to send it

@user_11e7e8 

Did that info work for you ? Please respond here on these public forums.