BungeeCord IPv6 Support.

日本語版の記事もありますので、読める方はそちらも。

BungeeCord support IPv6 since Jan/2016.

However, it might be somehow difficult for some people to set properly.

    lobby:
       motd: 'The IPv6 backend server!'
       address: [2400:1234:abcd:1122:3344:5566:7788:9900]:25566
        restricted: false
    main:
        motd: 'XXXX's Minecraft server!!'
        address: [2400:1234:abcd:1122:3344:5566:7788:9900]:25567
        restricted: false

If we wrote like above in config.yml, get this error.

20:55:01 [SEVERE] Exception in thread "main"
20:55:01 [SEVERE] while scanning a plain scalar
in 'reader', line 10, column 15:
address: [2400:1234:abcd:1122:3344:5566:77 ...
^
found unexpected ':'
in 'reader', line 10, column 19:
address: [2400:1234:abcd:1122:3344:5566:7788:9 ...
^
Please check http://pyyaml.org/wiki/YAMLColonInFlowContext for details.

20:55:01 [SEVERE] at org.yaml.snakeyaml.scanner.ScannerImpl.scanPlain(ScannerImpl.java:2013)
20:55:01 [SEVERE] at org.yaml.snakeyaml.scanner.ScannerImpl.fetchPlain(ScannerImpl.java:1046)
20:55:01 [SEVERE] at org.yaml.snakeyaml.scanner.ScannerImpl.fetchMoreTokens(ScannerImpl.java:401)
20:55:01 [SEVERE] at org.yaml.snakeyaml.scanner.ScannerImpl.checkToken(ScannerImpl.java:226)
20:55:01 [SEVERE] at org.yaml.snakeyaml.parser.ParserImpl$ParseFlowSequenceEntry.produce(ParserImpl.java:629)
20:55:01 [SEVERE] at org.yaml.snakeyaml.parser.ParserImpl$ParseFlowSequenceFirstEntry.produce(ParserImpl.java:617)
20:55:01 [SEVERE] at org.yaml.snakeyaml.parser.ParserImpl.peekEvent(ParserImpl.java:158)
20:55:01 [SEVERE] at org.yaml.snakeyaml.parser.ParserImpl.checkEvent(ParserImpl.java:143)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeSequenceNode(Composer.java:199)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:153)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:231)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:155)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:231)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:155)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeMappingNode(Composer.java:231)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeNode(Composer.java:155)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.composeDocument(Composer.java:122)
20:55:01 [SEVERE] at org.yaml.snakeyaml.composer.Composer.getSingleNode(Composer.java:105)
20:55:01 [SEVERE] at org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:120)
20:55:01 [SEVERE] at org.yaml.snakeyaml.Yaml.loadFromReader(Yaml.java:481)
20:55:01 [SEVERE] at org.yaml.snakeyaml.Yaml.load(Yaml.java:412)
20:55:01 [SEVERE] at net.md_5.bungee.conf.YamlConfig.load(YamlConfig.java:63)
20:55:01 [SEVERE] at net.md_5.bungee.conf.Configuration.load(Configuration.java:65)
20:55:01 [SEVERE] at net.md_5.bungee.BungeeCord.start(BungeeCord.java:265)
20:55:01 [SEVERE] at net.md_5.bungee.BungeeCordLauncher.main(BungeeCordLauncher.java:55)
20:55:01 [SEVERE] at net.md_5.bungee.Bootstrap.main(Bootstrap.java:15)

To solve this error, you must quote the address(es).

    lobby:
        motd: 'The IPv6 backend server!'
        address: '[2400:1234:abcd:1122:3344:5566:7788:9900]:25566'
        restricted: false
    main:
        motd: 'XXXX's Minecraft server!!'
        address: '[2400:1234:abcd:1122:3344:5566:7788:9900]:25567'
        restricted: false

================================

If you still have problem, you can try port testing.

IPV6 Scanner | Online Port Scan

 Online Port Scanner IPv6 - SubnetOnline.com