Nighthawk AC1900 R700 question

[oklahamas]

I bought an AC1900 and connected to my modem and set it up. I then unplugged it from the modem to move to my office (cable connection doesn’t work in my office so I can’t move the modem). My office does have a phone line that my printer is hooked up to, but there are no Ethernet ports anywhere in my house.

I was under be impression that I could use the AC1900 as an internet extender to connect to my desktop to the Nighthawk via Ethernet, as there is nowhere else to connect my desktop in this room. Did I get the wrong device? Can I hook my nighthawk into the phone line? Does the AC1900 always have to be hard ported into the Modem?

[plemans]

routers need an incoming ethernet connection. 

Some have an extender mode but you'd have to set it up with that mode. And if you have a modem only device, thats not possible either. 

The phone line isn't an ethernet connection and can't carry the data an ethernet cable can. 

What modem do you have?