As quoted from the linked post.
It looks like you’re part of one of our experiments. The logged-in mobile web experience is currently unavailable for a portion of users. To access the site you can log on via desktop, the mobile apps, or wait for the experiment to conclude.
This is separate from the API issue. This will actually BLOCK you from even viewing reddit on your phone without using the official app.
Archive.org link in case the post is removed.
Yay! Nice job! Your page is blocked for me at work but I’ll subscribe when I get home. Do you know, under the instance settings it says “allow instances” do I need to add anything there?