I can't connect the Roku to the router via WiFi because it needs a username and password login, rather than just the password, which the Roku doesn't seem to be able to do. I also can't check the settings on the router, as it's dorm WiFi and managed by the university.
A network that requires you to log in by entering a username and password into a web page via a web browser is the reason Roku developed its Hotel/Dorm Connect System.
This Roku page explains the process: https://support.roku.com/article/215058118
I've checked that out, but that's not the problem I'm having. The username and password aren't being requested by a web page, they're being required to sign into the locked network, the same way just a password would be used with any other locked network. A screenshot of the page it shows me on my phone is enclosed
