ipv6 over VPN tunnel

I'm having an ipv6 problem that's plagued me for some time. (IPv6 routing over VPN) the goal is to use a HurricaneElectric v6 tunnel to get v6 on my laptop, no matter where I am by using my VPN.

I'm going to be overly-detailed here, so settle in.

Network layout:

svr1 --- vpn --- laptop

• svr1 is a Linux OpenVPN client with a static v4 and HE's ipv6 tunnel.

• vpn is a Linux OpenVPN server (amongst other things). it has a dynamic v4 address and as such, cant be used with HurricaneElectric's tunnel.

• laptop is an OSX laptop and OpenVPN client

Interfaces:

• HE gateway: 2001:470:a:ed::1

• svr1 v6: 2001:470:a:ed::2

• srv1-tap: 2001:470:a:ed::20

• laptop-tap: 2001:470:a:ed::99

what I'd like:

HE --- svr1 --- (vpn) --- laptop

the problem hinges on the fact that I can make this set up work, but only under certain conditions.

for example, I connect up everything, ping6 2001:470:a:ed::2 (and beyond) is ICMP unreachable. as soon as I ping6 2001:470:a:ed::20 (the next hop). this kind of problem existed when I first set up the tunnel on srv1, but appears to have gone away with the addition of 'metric 1' to the interface declaration. I have however replicated this on vpn, although I havent yet tested the 'metric 1' component. I have been unable to find the 'metric' command on OSX, but I have found a number of people having issues with ipv6 on OSX

I'm looking for some sort of solution. I'd prefer static routes, no extra prefixes, but at this point, I'm willing to try anything. I've tried radvd, ipv6 on vpn, prefix (albeit probably incorrectly). I have almost no ipv6 experience, so assume I know nothing.