Cannot get my modem/router to connect to the internet

I tried Firefox browser. I cleared the browser history and cashe before attempting it. I did another factory reset and connected the router to my laptop via an Ethernet cable. When I launched Firefox it opened to a page with a row of letters in boxes. There was a statement at the top stating that I must login to the network before I could access the internet. There was a tab on the right of the page stating “open network login page”. I clicked on it but once again I got the page to reset my password and security questions. Once again I filled the information and once again the “next” button was inoperable. I am at a loss as to why I am not getting the actual login page, or the fact that the next button does not function when I try the reset of the password. I have been fooling with this thing since yesterday morning!