How can I manage modem and router settings without a phone app?

I used to be able to log into the admin interface for my Xfinity router, to manage QoS and other settings. Now it tells me I need an app. It appears there is not a way to do this on a PC. Why not? What about people who do not have smarttphones? I'm sure it saves the company money to disallow people from messing up settings unwittingly, but for people who are skilled and know what settings they need, it's frustrating to not be able to change them myself. No Windows app?