在 dd-wrt 下，能够获取到 ipv6 地址，但是无法访问 ipv6 网络，大概是怎么回事？

校园网，ipv6是不限流量的。我想用dd-wrt直接l2tp或OpenVPN到我的vps.当然是通过ipv6的。
在配置过程中，对ddwrt启用ipv6，可以或得到一个2001开头和一个2002开头的ipv6地址，但是无法访问网络。
访问内网里的ipv6正常。
求助各位大神，大概是怎么回事？
1、下面是路由表
root@DD-WRT:~# ip -6 route
2001:cc0:2020:4011:20c:43ff:fe30:5277 dev br0 proto kernel metric 256
2001:cc0:2020:4011::/64 dev br0 proto kernel metric 256 expires 2590771sec
2001:cc0:2020:4011::/64 dev vlan2 proto kernel metric 256
2001:cc0:2020:4011::/64 dev ra0 proto kernel metric 256
2001:cc0:2020:4011::/64 dev vlan1 proto kernel metric 256
2002:7c10:5abe:4::/64 dev br0 proto kernel metric 256 expires 171571sec
fe80::/64 dev eth2 proto kernel metric 256
fe80::/64 dev br0 proto kernel metric 256
fe80::/64 dev vlan1 proto kernel metric 256
fe80::/64 dev ra0 proto kernel metric 256
fe80::/64 dev vlan2 proto kernel metric 256
fec0:0:0:4::/64 dev br0 proto kernel metric 256 expires 171571sec
unreachable default dev lo proto kernel metric -1 error -128
ff00::/8 dev eth2 metric 256
ff00::/8 dev br0 metric 256
ff00::/8 dev vlan1 metric 256
ff00::/8 dev ra0 metric 256
ff00::/8 dev vlan2 metric 256
unreachable default dev lo proto kernel metric -1 error -128

2、这个是获取到的ipv6地址。
root@DD-WRT:~# ifconfig
br0 Link encap:Ethernet HWaddr 00:0C:43:30:52:77
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: 2002:7c10:5abe:4:20c:43ff:fe30:5277/64 Scope:Global
inet6 addr: fec0::4:20c:43ff:fe30:5277/64 Scope:Site
inet6 addr: 2001:cc0:2020:4011:20c:43ff:fe30:5277/64 Scope:Global
inet6 addr: ::1:20c:43ff:fe30:5277/64 Scope:Global
inet6 addr: fe80::20c:43ff:fe30:5277/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:23390 errors:0 dropped:10 overruns:0 frame:0
TX packets:13133 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1965042 (1.8 MiB) TX bytes:7188676 (6.8 MiB)

br0:0 Link encap:Ethernet HWaddr 00:0C:43:30:52:77
inet addr:169.254.255.1 Bcast:169.254.255.255 Mask:255.255.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

eth2 Link encap:Ethernet HWaddr 00:0C:43:30:52:77
inet6 addr: fe80::20c:43ff:fe30:5277/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:23985 errors:0 dropped:0 overruns:0 frame:0
TX packets:13178 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2445079 (2.3 MiB) TX bytes:7233020 (6.8 MiB)
Interrupt:5

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MULTICAST MTU:16436 Metric:1
RX packets:188 errors:0 dropped:0 overruns:0 frame:0
TX packets:188 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:12020 (11.7 KiB) TX bytes:12020 (11.7 KiB)

ra0 Link encap:Ethernet HWaddr 00:0C:43:30:52:A8
inet6 addr: fe80::20c:43ff:fe30:52a8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:71 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:17157 (16.7 KiB) TX bytes:0 (0.0 B)
Interrupt:6

vlan1 Link encap:Ethernet HWaddr 00:0C:43:30:52:77
inet6 addr: fe80::20c:43ff:fe30:5277/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:23984 errors:0 dropped:46 overruns:0 frame:0
TX packets:13121 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2013307 (1.9 MiB) TX bytes:7157306 (6.8 MiB)

vlan2 Link encap:Ethernet HWaddr 00:0C:43:30:52:78
inet6 addr: fe80::20c:43ff:fe30:5278/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:50 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:14200 (13.8 KiB)

谢谢各位大大~！