Error 521: Webserver is down, but webserver is up (and only 1 domain not working?)

When visiting a static file, https://whirlocal.io/license.txt, it briefly loaded with a “too many redirects” error and now is showing the 521 error as well?

Edit: Spamming refresh loads the text file about 5-10% of the time, while showing the 521 error instantly other times.