When you get service to your home (typically), you need to convert the signal and that is the job of a modem. Next, you have to direct the signal and that is the job of a router as it "routes" the data. Most cases, a provider will set up a single device that is a modem-router as it contains both parts mentioned. If you want to use this excellent router you are asking about, you really only need a separate modem. Either your provider can get you one (rent) or you can purchase one. Just make sure that the modem is designated as DOCSIS 3.1 (if possible or a higher number).
In short the unit is the router itself and you need the modem or equivalent part to connect to your provider.