Comment 4 for bug 704812

I've since done my IPv6 setup at home and I can't reproduce this, with a DHCPv6 server or using autoconfiguration. I notice there are some differences though, you're also setting up a teredo tunnel, so could it be related? I'm not hugely familiar with the setup, but it looks like you would be trying to announce an IPv6 range to the network using teredo, while also having NM maintain an IPv6 address for the interface?

I may well be reading this wrong though, but I'd check if it's possible to turn debugging way up for miredo (if that's indeed what you're using) to make sure it's not what's adding the default route via dev wlan0. Sadly there is too little information in the attached syslog to tell whether it's NM -- so you also might want to stop NM (sudo stop network-manager), then start it again as such:

sudo /usr/sbin/NetworkManager --no-daemon --log-domains=IP6,DHCP6,CORE,DEVICE --log-level=DEBUG

and attach the resulting log (after making sure it doesn't contain info you feel is sensitive).