Wifi connection issues ever since upgrading to Technicolor CGM4331COM

Ever since I upgrade to a faster interent and Xfinity sent me their Technicolor CGM4331COM modem/router, I've been having problems with multiple devices connecting via wifi. My kids XBOX 360 will no longer connect and now my Dell Inspiron 15 5000 Series laptop doesn't even display the networks. There is no way obvious for me to contact Xfinity support via email and I don't have time to spend an hour on  the phone with them to trouble shoot. I either want exact step by step layman's terms instructions to resolve the issue or send me a new router/modem that works.