I have a problem with IPv6 over Teredo in Win 8.1 x64 and BDTS 2016 20.0.29.1517
When "Network type" for my WiFi adapter in firewall settings of BDTS is "public", I can't connect to no one IPv6 sites, and tests of IPv6 connectivity show me, that it's not supported.
When "Network type" for my WiFi adapter in firewall settings of BDTS is "trusted", I have no problem with IPv6. 
Changing "stealth mode" and "generic" is don't influence result.
I uninstalled and installed again BDTS. Problem was resolved, but just for short time and appeared after a few of restarts.