Can’t believe this is real, apparently since 2018 you can’t install gems on a machine that has working IPv6 support? There is a trillion fixes and workaround around on the internet, but the only one I could get to work was turn off IPv6 support on my mac, when the actual fix would really have to be done by rubygems.org: either remove the AAAA records on your domain or actual set up IPv6 (preferably the latter of course).
Truly shocked that such a popular tool hasn’t been fixed within 4 years..