Today my broadband was switched over from 2degrees to Spark, and even though it was mentioned on here in the New Spark Broadband Offerings topic that you keep the 2degrees supplied Fritzbox when out of contract with 2degrees, you don't, as they want it back, even after being with them for 5 and a bit years. 
Anyway, so now I am looking at routers, and went to check out one a bit earlier, this was in Harvey Norman. The specific model I looked at, is this one D-Link DIR-X1860 EXO AX1800 Wi-Fi 6 Router | Harvey Norman New Zealand 
The Harvey Norman salesman said it won't work with fibre as you will need a modem too. In my head, I am saying to myself - no, you just need the router, which connects to the ONT and in the router you put your username and password and set up the other settings, which then gives you WiFI and Ethernet connectivity in the house. 

So, am I right in my thinking or was the Harvey Norman salesman right and I need both a modem and router or modem/router combined?