I recently reinstalled the OS on my server (due to a lot of misconfiguration, I thought it would be easiest to start again) following the guide on the wiki: 

It installed correctly, and now I am working through the "Things you might like to change after install" part. I set up the cacher and NTP but I am completely stumped on IPv6. According to "ifconfig" IPv6 is there (I have an inet6 address) so I tried to ping6 ipv6.google.com and it failed as i suspected.

The next thing I tried was just adding my settings to /etc/network/interfaces:
iface eth0 inet6 static
pre-up modprobe ipv6
# Perhaps you will only use this one for web serving
    address fe80::216:5eff:fe00:1e5
    netmask 64
    gateway 2001:ba8:1f1:f004::1

but that didn't work either...does anybody have any idea how I can enable v6?

Thank you!