https://www.polarxiong.com/archives/%E8%A7%A3%E5%86%B3ubuntu%E4%B8%8Bipv6%E8%BF%9E%E6%8E%A5%E4%B8%80%E6%AE%B5%E6%97%B6%E9%97%B4%E5%90%8E%E5%B0%B1network-is-unreachable.html
https://www.baidu.com/s?wd=ubuntu%E6%B2%A1%E6%9C%89ipv6&pn=30&oq=ubuntu%E6%B2%A1%E6%9C%89ipv6&ie=utf-8&rsv_idx=1&rsv_pq=cc2d82e3000a77d6&rsv_t=bfaaloRBvsxh7Qt742pCQXpc92v8et2mGcbb1PeF2VtwW0IJDKjYuKSElxE
https://www.baidu.com/s?wd=ubuntu16.04%20ipv6&pn=10&oq=ubuntu16.04%20ipv6&ie=utf-8&rsv_idx=1&rsv_pq=a5453c6a00105ede&rsv_t=5a7ej1gTg38HI61LW0xFL5hO81rDMS3VPOafPu7Xw6bZoRTXRQuR%2Fngcw0k
http://blog.csdn.net/xuluohongshang/article/details/76136594
http://blog.csdn.net/qq_18820397/article/details/51171220
根据这个方法修改，然后加载所有配置，~$ sudo sysctl --system #加载所有的配置文件，像/etc/sysctl.d/*等
原先连的是实验室网，断开后链接tjuwlan，然后支持ipv6了。如果第一遍不行就多连两次tjuwlan