Sonos connection with xb7 gateway

I have a new xfininity gateway, Model Numbers: CGM4331COM, Friendly Model Name: XB7. I am trying to connect my Sonos speakers to the WiFi network, but the Sonos app will not connect to the network. I am using the 2.4 ghz WiFi network. I have been on the phone with Sonos tech support, but they are unfamiliar with the router and have been no help. I am close to purchasing my own modem and using my own router unless I can get my speakers to work. Now I have one speaker plugged directly to the router with an Ethernet cable, but still no network connectivity.