I recently purchased a DIR-860L and have been attempting to configure it to get IPv6 working. All of my devices can get IPv6 internet access when connected directly to my ISP's network termination device, however with the DIR-860L none of them are able to get IPv6 WAN access.
I have compiled an image here: http://i.imgur.com/dnWSzKv.png containing screenshots of the DIR-860L's current IPv6 configuration page and the Windows and DIR-860L IPv6 status pages. As can be seen addresses do look like they're being assigned to clients, but no matter what options I select in the router for IPv6 none of the clients, Windows or Android, receive IPv6 internet access. However pinging IPv6 addresses from the DIR-860L's web interface does work, so it would seem the IPv6 WAN settings are correct in the router.
I've disabled all software firewalls, and all of the DIR-860L's internal firewall settings, and attempted disabling IPv4 even to test things, but nothing seems to work. If someone has any idea how to get things working it'd be greatly appreciated.