i have same wifi provider. you have dual band 2.4 and 5 ghz on network. you need to try both wifis setup on your comcast. if you have only one, you need to call comcast and ask if both bands have each owns network name to login. thats only way to be sure.i had g3. ask xfinity to help you. ask for ADVANCED GATEWAY SUPPORT.
Also you have vzw mobile internet. so ask chat too in vzw same thing.