It looks like they sometimes have problems with the accessibility of their site. I can not reach that at times either. but that may be due to the many updates for the new page
Possibly or may be routing issues I know last week or two a bunch of hosts have had issues due to broken fibers in the USA but thats nothing that can be helped crap happens. Site seems mostly reliable maybe someone should mirror the whitepaper or maybe they should serve it from github for availability
I never had issues to get on the website or their whitepaper. Maybe the team update some things or they test some new features.