You need to use https on port 443, so https://cav.ac
Unsecured connections are not really supported anymore. On most browsers, the automatic redirect from http to https should work, although i don't test this regularly anymore. But i short test showed that a connection to the server over insecure http (port 80) returns a 301 Moved Permanently with a pointer to Location: https://cav.ac/
The other possibility is that your IP is somehow on one of my firewall blacklists. Can you send me your IP via private CB ("/msg cavac my ip is 126.96.36.199") so i can check my logs?
perl -e 'use Crypt::Digest::SHA256 qw[sha256_hex]; print substr(sha256_hex("the Answer To Life, The Universe And Everything"), 6, 2), "\n";'