If curl tries to connect over ipv6, it is because it got an IPv6 address for the given host and IPv6 works on your system. It is then supposed to try both IPv4 and IPv6 (which is what is called "happy eyeballs") and use the one that connects first. You can force ipv4-only with the dedicated option and you can of course put that in your .curlrc file etc or rebuild curl from source with IPv6 knowledge removed.

Those are still just work-arounds, curl should work out these details by itself. For me it is a bit hard to debug though since I've not been able to repeat this problem in my end.

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** [bugs:#1424] happy eyeballs problem with host unaccessible over ipv6**
**Status:** open
**Created:** Fri Sep 19, 2014 05:50 AM UTC by Michael Heuberger
**Last Updated:** Fri Sep 19, 2014 07:48 AM UTC
**Owner:** Daniel Stenberg
Running `curl https://sublime.wbond.net/channel.json` in the console tell me, its unreachable:
$ curl https://sublime.wbond.net/channel.json
curl: (7) Failed to connect to sublime.wbond.net port 443: Network is unreachable
But I can download that json from any browser instance.
Weird. How come?
Here more info. I am on Ubuntu 14.04:
$ curl -V
curl 7.37.1 (x86_64-pc-linux-gnu) libcurl/7.37.1 OpenSSL/1.0.1f zlib/1.2.8 libidn/1.28 librtmp/2.3
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtmp rtsp smtp smtps telnet tftp 
Features: AsynchDNS GSS-Negotiate IDN IPv6 Largefile NTLM NTLM_WB SSL libz TLS-SRP 
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