I discovered just yesterday that Verizon home internet blocks archive.is. Changing the router DNS from their default to openDNS fixed the problem for me, so it looks like they made only a nominal effort to block it.
That seems ludicrous, given that after a DNS lookup, the next thing anybody does is to send an HTTP request, which obviously reveals that same IP address to the archive servers.
So it's an obvious and blatant lie by Cloudflare, and I wonder what their real reason is.