220.127.116.11 fails to resolve is-cf.help.every1dns.net (used by https://18.104.22.168/help) if any part of is-cf is uppercase. This breaks the site for DNS resolvers such as Knot resolver which randomly capitalise letters.
The same appears to be true for 22.214.171.124 and 126.96.36.199. It appears that
ns.help.every1dns.net doesn’t support dns-0x20 and treats queries as case sensitive.
dig is-cF.help.every1dns.net @ns.help.every1dns.net ; <<>> DiG 9.10.6 <<>> is-cF.help.every1dns.net @ns.help.every1dns.net ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 3832 ;; flags: qr aa rd; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;is-cF.help.every1dns.net. IN A ;; AUTHORITY SECTION: help.every1dns.net. 0 IN SOA help.every1dns.net. dns.cloudflare.com. 2018100101 21600 3600 604800 0
ns.help.every1dns.net always responds with an NXDOMAIN unless the request comes via 188.8.131.52 which is how the site determines whether the request is through 184.108.40.206/DoT/DoH.
Additionally case sensitivity only matters in the is-cf part.
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This should be fixed now, sorry for the issues.