The access is not blocked but sometimes not available because the site is down - when we work on the server for installing a new Nexus site version e.g., this happens since we do not yet have a mirror server; and since it usually does not take too long we do not show a maintenance mode page. I hope this does not cause too many inconveniences! And you are right, we see a really growing importance and usage of Nexus and thus may extend the infrastructure in near future.
Best wishes,
Andreas
