Just to make absolutely sure: you are POSITIVE that the device you’ve been renting is a MoCA-WAN router, and NOT a cable modem?

In the US at least, most of the single-unit devices that receive a coax input are DOCSIS 3.x, not MoCA. They are combining two pieces of hardware in a single physical unit: a docsis modem and a router.

Prior to having fiber internet, when my provider was Comcast, I owned two separate devices instead of renting the single device from my ISP: a DOCSIS 3.1 modem from Arris, and a standard Ethernet router

Just want to make sure you are absolutely confident about what your ISP is actually providing before you spend money on new hardware :)