Internet Issue CM500-100NAS

I have a CM500-100NAS modem, hooked with an Asus RT-AC68U router, and a TP-Link 5 port switch. The connection was typically router into modem, switch into router. Everything relatively was fine, today around 11am I lost wifi connection. I've rebooted both devices, several times, and I'm getting no internet through the router or switch. THe only way I'm getting internet is through a single computer, plugged directly into the modem after it's rebooted with the computer plugged in. When I try the switch directly through the modem, it'll only (sometimes) connect with the last computer it connected with and nothing else. I have Xfinity internet, and they say it's nothing wrong their end, has to be the settings in the devices. I did factory reboot the modem but cannot made heads or tails of exactly what details it gives me, it's very minimal. The router settings I can only so far access by the phone. I may be able to get it by computer if I finangle it. What settings do I need have on what to make this back to normal? My wife and I both use the internet, and I also need it for my work, it's required (Work from home).