Following communities on Masto?

Looks like you should be able to copy/paste the URL of the community in your Masto search bar, such as https://beehaw.org/c/politics, but this seems to only work with the Beehaw technology community (https://beehaw.org/c/technology). A nondescript 500 server error is returned when I try any others. Is this expected? Is there some kind of toggle for each community that allows/disallows following from other Federated instances?