The launcher won't work over IPv6. My network has DNS64+NAT64 at a router/ISP level, so there's no need for the remote host to support IPv6, but the client clearly does not:
Java 7 had (may still have) an issue where it's dual stack didn't behave correctly. In the past this would manifest as the stack thinking it should communicate via IPv6 and it would not fall back to IPv4 if that did not work.
In the past this would manifest as the stack thinking it should communicate via IPv6 and it would not fall back to IPv4 if that did not work.
That would be the exact opposite of what's happening here. Java is assuming there's an IPv4 address and routes, but there are none (excepto for 127.0.0.1), and isn't using IPv6 at all.
The point is that Minecraft makes a connection by name and doesn't care or know about the protocol. The Java 7 stack resolves that name and decides how to connect to the resulting address, and it has a known history of f-ing it up. It was one of the major problems people posted about here when Java 7 first came out. How Java 7 determines which protocol to use is a mystery, since the people who had trouble had no IPv6 connectivity, although their windows configuration might have included interfaces with IPv6 autoconfiged addresses. In the past those people would use a Java option to force IPv4 use, perhaps you need to use one to force IPv6 use.
EDIT:
Okay, went digging and found out the reason why that Java 7 issue has mostly disappeared. It appears that because it was such a common problem, Mojang stuck the 'fix' into minecraft.exe, so now it always prefers IPv4 (see https://bugs.mojang.com/browse/MC-3776).
It sounds like you might be able to avoid this issue by downloading the JAR launcher and using that. To do that you would go to https://minecraft.net/download and click the link for "Show all platforms", then download the JAR under the section "Linux/Other" You can then launch it via "java -jar minecraft.jar" which you could put into a bat file...
The point is that Minecraft makes a connection by name and doesn't care or know about the protocol. The Java 7 stack resolves that name and decides how to connect to the resulting address, and it has a known history of f-ing it up. It was one of the major problems people posted about here when Java 7 first came out. How Java 7 determines which protocol to use is a mystery, since the people who had trouble had no IPv6 connectivity, although their windows configuration might have included interfaces with IPv6 autoconfiged addresses. In the past those people would use a Java option to force IPv4 use, perhaps you need to use one to force IPv6 use.
EDIT:
Okay, went digging and found out the reason why that Java 7 issue has mostly disappeared. It appears that because it was such a common problem, Mojang stuck the 'fix' into minecraft.exe, so now it always prefers IPv4 (see https://bugs.mojang.com/browse/MC-3776).
That's not the case in my scenario, I'm not using the windows binary (exe), nor windows.
It sounds like you might be able to avoid this issue by downloading the JAR launcher and using that. To do that you would go to https://minecraft.net/download and click the link for "Show all platforms", then download the JAR under the section "Linux/Other" You can then launch it via "java -jar minecraft.jar" which you could put into a bat file...
That's what I'm doing already, since I play on ArchLinux systems.
Bootstrap (v5) Current time is Jun 5, 2014 12:27:27 PM System.getProperty('os.name') == 'Linux' System.getProperty('os.version') == '3.14.5-1-ARCH' System.getProperty('os.arch') == 'amd64' System.getProperty('java.version') == '1.7.0_55' System.getProperty('java.vendor') == 'Oracle Corporation' System.getProperty('sun.arch.data.model') == '64' Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 2/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 3/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 4/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 5/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 6/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 7/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 8/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 9/10) Exception: java.net.ConnectException: Network is unreachable Downloading: https://s3.amazonaws.com/Minecraft.Download/launcher/launcher.pack.lzma (try 10/10) Exception: java.net.ConnectException: Network is unreachable Unable to download remote file. Check your internet connection/proxy settings. FATAL ERROR: net.minecraft.bootstrap.FatalBootstrapError: Unable to download while being forced at net.minecraft.bootstrap.Bootstrap.execute(Bootstrap.java:95) at net.minecraft.bootstrap.Bootstrap.main(Bootstrap.java:381) Please fix the error and restart.Just so you know the network and NAT64 work fine:
This is a critical, high-level issue, since it prevents download of the game client, and will gradually affect more and more users.
As I mention in my initial post, this is not a dual stack scenario, but an IPv6 network, with NAT64 at a router level.
That would be the exact opposite of what's happening here. Java is assuming there's an IPv4 address and routes, but there are none (excepto for 127.0.0.1), and isn't using IPv6 at all.
EDIT:
Okay, went digging and found out the reason why that Java 7 issue has mostly disappeared. It appears that because it was such a common problem, Mojang stuck the 'fix' into minecraft.exe, so now it always prefers IPv4 (see https://bugs.mojang.com/browse/MC-3776).
It sounds like you might be able to avoid this issue by downloading the JAR launcher and using that. To do that you would go to https://minecraft.net/download and click the link for "Show all platforms", then download the JAR under the section "Linux/Other" You can then launch it via "java -jar minecraft.jar" which you could put into a bat file...
That's not the case in my scenario, I'm not using the windows binary (exe), nor windows.
That's what I'm doing already, since I play on ArchLinux systems.
EDIT:
I've created this issue now that I'm aware of the existance of a bug tracker:
https://bugs.mojang.com/browse/MCL-2627