It seems that once again Blizzard have some IPv6 issues that are impacting World of Warcraft.
This should be simple for them to fix. They have connectivity to their network, which seems to be very good (via LINX) with low pings, but the individual servers their end do not seem to be working on the IPv6 addresses the client is trying.
This could simply be a change of IPv6 SLAAC address following hardware changes, or could be something else, we don't know. They are not interested in investigating.
Normally a failure in one IP protocol is not a huge issue as clients fall back to the other version, e.g. trying IPv6 first then legacy IPv4. However the WoW client seems not to be doing this, simply hanging and eventually giving an error.
Obviously this has been reported to Blizzard, but I am sorry to say that they are taking the backwards step of taking no notice of IPv6 issues, effectively withdrawing support for the current version of Internet Protocol, IPv6
As such, customers may have to change their config on their game client not to try IPv6. This is obviously not something we would normally recommend as it removes the usual redundancy of having both protocols. It also gives the mistaken impression that IPv6 is somehow unreliable, rather than the more accurate impression that Blizzard are unreliable.
Hopefully they will fix it eventually. We have yet to see any official statement as to withdrawal of support for IPv6, a move that is very unusual for any company to take.
Blizzard have now said they have engineers working on this. No ETA.
An update from Blizzard suggests they have made changes to address this, but tests suggest it is not yet resolved, so still chasing.
Blizzard have made a number of changes to fix this issue. It is not quite fixed for everyone according to my tests, so they are working on it still.
Blizzard have said: "As mentioned previously, the game client is designed to take advantage of the IPV6 options simply by ticking the IPV6 option ingame and restarting the game. As IPV6 comes available, you will be automatically join it."
This is odd, as we have had IPv6 since 2002 and Blizzard have had it since 2011, so by that statement we should "join it".
At this point it is still not working in my test, still a routing loop within Blizzard's network.
As Blizzard mistakenly marked my ticket resolved, I have opened a new one. Sorry we don't have any more update on this.
There is a Blizzard EU forum post on this matter. http://eu.battle.net/forums/en/wow/topic/17612333772?page=1#post-8
Blizzard have finally resolved the issue.