Apparently the Fifth head of the Hydra, Memelord of Romulus (according to people on !risa@startrek.website thanks guys)
I have quantum fiber at home, and I don’t use their provided modem. The fiber terminates outside my house, and a cat5 cable was run into my utility closet, which plugs into the modem.
I have a Unifi USG router, and have the WAN configured for PPPoE login (you will have to get that login from the provided modem, or ask their support people).
You also have to set the VLAN ID to: 201
So as long as you can set VLAN ID on your WAN, and do PPPoE, you shouldn’t need their provided modem.
In my instance, that fiber cable terminates outside of my house. I didn’t realize CenturyLink ever routed fiber inside the house.