Setting up Nextdns for the router

I'm wanting to set up NextDNS for the router and am having some trouble. When I go to routerlogin.net or http://192.168.0.1/ ot the 1.1 variation, it just takes me to paswword reset over and over again. Even after I reset password it has me do it again and again. What am I missing?  Again, just wanting Nextdns to run through the router so that all wifi devices like Chromebooks and PS3 will have parental control. I do have the Nighthawk app on my android phone but it has limited configurations.