It does, but it so happens that Certbot only added IPv6 support in --standalone a week ago, thanks to efforts by @erica.
Since you're not running certbot-auto, you probably don't have a recent enough version of Certbot to have IPv6 support with --standalone, due to this bug. If you install another copy of Certbot with the certbot-auto method, you should.
@rg305's suggestion is right for selecting a port number (443 vs. 80), but I suspect there's also a deeper problem at work here.
