I'll pass it on. I'll note that when I tried to create an archive link with archive.ph, its crawler also reported that it failed with 403. The archive.org (unrelated organization) crawler worked as expected. Which makes me think it's probably not specific to your setup, but some sort of anti-DOS protection gone awry. The sudden HN load probably looked abnormal, and it erroneously started blocking legitimate requests from some parts of the internet.
