Would like to use my own router

I recently moved in to a new construction home and had a tech come and pull fiber to my telecom box, install a Nokia ONT... And then he put a Xfinity XER10 in my media enclosure (kinda)

For one: The XER10 is too large to fit in my enclosure and I can't close the door. I patched port1 to my POE switch that powers my WAPs and everything else around the house. But it's not uplinking / passing DHCP info to clients, and rather than jumping through hoops to figure this out.

Can we just remove the XER10 from my account, setup the ONT to connect to my router, and everyone lives happily ever after?