User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:46.0) Gecko/20100101 Firefox/46.0 Build ID: 20160503215307 Steps to reproduce: Connected to http://ismyipv6working.com/ Actual results: Saw a Sulking Panda instead of a Running Unicorn Expected results: Seen a Running Unicorn as on Microsoft Edge. Happens on both Windows 7, Windows 10 and Linux. Behaviour is similar to to Chrome/Chromium. IPv6 connectivity is through a he.net tunnel. Connecting explicitly to IPv6 sites works fine. Seems to the the result of "Happy Eyeballs" or "Fast Fallback" or whatever that **** is called. See: http://www.test-ipv6.com/faq_avoids_ipv6.html and bug 920367. Because of this unwarranted "Fast Fallback" feature (that seems to be new), FF is connecting to IPv4 instead of fully functioning IPv6 just because of inherent latencies due to tunnelling. Need: 2 configuration variables: network.IPv6.disableHappyEyeballs: default FALSE network.IPv6.HappyEyeballsTimeout: default 300 This will provide behaviour as current, with the ability to tweak it as needed. Timeout values should NOT be hardcoded anyway. If Chrome/Chromium makes bad design decisions no reason for FF to do the same. I care about FF and hence filing this bug here.
Please note the folloiwng: 1) Also http://www.test-ipv6.com/ gives me a 10/10 2) SixOrNot panel shows that the sites have IPv6 addresses
Severity: normal → major
Priority: -- → P3
We have the network.http.fast-fallback-to-IPv4 pref, which should do what you want.
Status: UNCONFIRMED → RESOLVED
Last Resolved: 2 years ago
Resolution: --- → INVALID
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