Nighthawk App

I have the Nighthawk AC1750 R6700 router, and cannot get the app to work for installation. I have a desktop and a laptop connected to the router's wifi network, and my phone shows that it is connected (strong wifi signal, entered the password), but it will not connect to the router. When I am trying to set up the router using the app, I can't get past the "WiFi Not Detected," portion to continue set up. 

I've gone into settings and joined the routers network, I've enabled local network access, I am not on a guest network, I am not in bridge mode.... I turned off cellular service on my phone, and when I do I lose all connectivity. So even though it appears it is connected to the router network, I am not getting any connection to it.

I've deleted and reinstalled the app, factory reset the router, and reconnected. I also cannot access routerlogin.net, as I get a message on the page that I need to connect to the wifi's router. But... I'm connecting to the page using the only wifi router I have.