When trying to access dev.gnupg.org using Safari (on the latest MacOS), the CSS and JS resources (served from different domains) do not load - failing with a "421" error generated by Apache. See attached screenshot. This has been going on for some time now.

This issue seems to be similar to the one discussed in https://serverfault.com/questions/916724/421-misdirected-request , and this appears to be a bad interaction between the Apache TLS/vhost handling and Safari trying to be efficient. I don't have direct access to an iPhone/iPad but I can imagine things failing there as well.

The least intrusive solution appears to be to use a separate certificate for each domain, instead of a single certificate with all names as alternatives.