I know my ISP's IPv6 status. That's not the issue. The issue is the new modems don't communicate with TWGS unless they have 6 to 4 pass through capability. TWGS doesn't recognize the new IPv6 structure, and as a result TWGS only reads your LAN IP.
I have found a work around for this problem however it does require some extra effort unless you have a static IP address.
By adding a secondary LAN IP to your server that is the same as your WAN IP will allow TWGS to accept connections and not end up with a binding error.
There are a few IP configuration programs out there that make this fairly easy, and will work fine until your router reboots or your WAN IP changes.
One program I found that works pretty well and is easy to use is:http://windows-ip-configuration-manager ... ormer.com/
Of course you still need to have port forwarding enabled or have your machine placed outside the NAT firewall.