I had a lot of trouble getting my Nintendo Switch to connect to the internet while staying at our otherwise lovely villa here in Bali. While trying to join a network it would give the “registration is required to use this network” warning, then launch the browser to try to show me the registration page.
Except instead of a registration page, it would just show the default conntest.nintendowifi.net page. This means that no registration was actually required and the Switch was online but, because it hadn’t passed registration, it thought it wasn’t and no services would work.