After enabling IPv6 curl github.com fails, succeeds with IPv4

Mayuresh <[email protected]> Tue, 21 Jul 2026 17:09:03 +0530

Newsgroups	gmane.os.netbsd.general
Message-ID	<[email protected]>

On NetBSD 10.1 amd64,

$ curl -V
curl 8.21.0 (x86_64--netbsd) libcurl/8.21.0 OpenSSL/3.6.3 zlib/1.3.1 libidn2/2.3.7 nghttp2/1.68.0
Release-Date: 2026-06-24
Protocols: dict file ftp ftps gopher gophers http https imap imaps ipfs ipns mqtt mqtts pop3 pop3s rtsp smtp smtps telnet tftp ws wss
Features: alt-svc AsynchDNS HSTS HTTP2 HTTPS-proxy IDN IPv6 Largefile libz SSL threadsafe TLS-SRP UnixSockets


    curl -i https://github.com
    curl: (35) TLS connect error: error:0A000410:SSL routines::ssl/tls alert handshake
     failure

But this succeeds:
    curl -4 -i https://github.com

In turn the git operations fail, as curl fails.

Suggests some IPv6 misconfiguration on my system?

-- 
Mayuresh