Same here on my dual-stack network. It is probably a result of the recent changes that allow registration of AAAA records in ampr.org, and people experimenting by adding an AAAA record for their hostname to see if that is working. Not a good idea to do that when it either does not point to the same system, or the services on that system (like http/https) are not configured to actually handle the IPv6 case. I have seen this problem before when I added IPv6 capability to my own network and the proxy at work: even some of the "big guys" got this wrong especially in the early days. AAAA record in DNS but IPv6 not actually working, or only for some protocols and not for others. And often no monitoring for IPv6, so nobody noticing. Usually, when this became obvious a slightly different domain name was used for IPv6 testing (e.g. adding a 6 or .ipv6. somewhere), and that is probably what people testing IPv6 on .ampr.org should do as well. Rob