gem cannot access rubygems.org

I didn't find /etc/gai.conf on MacOS, so as a workaround I just disabled IPV6 to download the gems. That worked for me.

'System Preferences' -> 'Network' -> Select WiFi -> click 'Advanced' button -> select 'TCP/IP' tab -> set the Configure IPV6 select to 'link-local only'.

api.rubygems.org is currently experiencing issues with IPv6 setup: this hostname has 4 IPv6 addresses, but responds on neither of them. Neither to ping, nor to TCP connection attempts. When you are running gem, your gem tries IPv6 addresses first and times out on them, not having time to even try IPv4 addresses.

The solution is to lower priority of IPv6 addresses for api.rubygems.org, so that gem will try IPv4 addresses first. In order to do it, put these lines into /etc/gai.conf:

---

# Debian defaults.
precedence  ::1/128         50
precedence  ::/0            40
precedence  2002::/16       30
precedence  ::/96           20
precedence  ::ffff:0:0/96   10

# Low precedence for api.rubygems.org IPv6 addresses.
precedence  2a04:4e42::0/32  5

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