Regarding (2), can you then explain why the code doesn't work? That seems very odd to me.

The happy eyeballs code is there to try connecting using both IPv4 and IPv6 at the same time and go with the one that connected first.

As nobody of us can repeat the problem nor understand why it happens, I'm not sure how to proceed with this!

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** [bugs:#1377] Regression in 7.35.0 to (at least) 7.37.0 related to IPv6 (on Windows?)**
**Status:** open
**Created:** Fri May 30, 2014 08:22 PM UTC by Luke-Jr
**Last Updated:** Sat May 31, 2014 09:17 PM UTC
**Owner:** Daniel Stenberg
My software uses libcurl as its socket layer via CURLOPT_CONNECT_ONLY. One user is reporting a regression connecting to http://stratum.f2pool.com:3333 (note, this is not a HTTP server) that we have isolated to 2d435c7fb5b7691e8ca1f3052e1eb5bcd8a4ea27 (trynextip: fix build for non-IPV6 capable systems). I am building libcurl with --enable-ipv6, but strangely enough, I don't think ENABLE_IPV6 is defined anywhere (lib/curl_config.h contains /* #undef ENABLE_IPV6 */). The user in question does not have IPv6 on his (Windows XP) system, so I am guessing that somehow libcurl is simply never trying IPv4 in this case.
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