I was not able to find the D-Link DIR-825 Rev B1 router here in the US, so I ended up with the D-Link DIR-615 Rev C1. It works flawlessly as my 6in4 endpoint, and as a RADVD server. Here are the settings I used: Make sure you are using a 6in4 static tunnel on your sixxs pop. I suppose it could work with heartbeat as well if you run a heartbeat client somewhere, but I have not tried. Get your tunnel details from https://www.sixxs.net/home/ and click on your tunnel id for the complete information. Make certain you have requested a subnet for the tunnel in question, or this will not work. Product Page: DIR-615 Hardware Version: C1 Firmware Version: 3.10NA IPv6 Connection is : IPv6 in IPv4 Remote IPv4 Address : (use sixxs tunnel pop ipv4 here) Remote IPv6 Address : (use sixxs tunnel pop ipv6 here) Local IPv4 Address : (use isp provided ipv4 here) Local IPv6 Address : (use sixxs tunnel your ipv6 here) Primary DNS Address : I left it blank since I do not have any RFC 5006 capable clients, and do not want to use DHCPv6. Secondary DNS Address : I left it blank since I do not have any RFC 5006 capable clients, and do not want to use DHCPv6. LAN IPv6 Address : Set to one of the addresses out of the /48 subnet allocated for your tunnel. e.g. if you subnet was 2001:db8::/48 use 2001:db8::1/64 as your LAN address. LAN IPv6 Link-Local Address : - automatically set Enable Autoconfiguration: Checked (ON) Autoconfiguration Type : Stateless Router Advertisement Lifetime: 120 If you have problems, you may want to upgrade your firmware and then reset your router back to factory settings before setting everything up again. This solved my initial problem with the DIR-615. Good Luck. --_Dave