They have something, I don't know if it's called a modem or not, but you don't need a modem yourself. Just the router is sufficient
My existing router isn't working, they say you need a gigabit router.
I have this router? Would it work with Fios? NETGEAR WiFi Router (R6230) - AC1200 Dual Band Wireless Speed (up to 1200 Mbps) | Up to 1200 sq ft Coverage & 20 Devices | 4 x 1G Ethernet and 1 x 2.0 USB ports ($49.99)