I played around with a Windows-Host behind an ipv4-NAT using Teredo. The Teredo-Host can reach most servers out there and a host behind a btexact-tunnel but not hosts behind sixxs or freenet6 . Both non-functioning routes go through "vpn1.teleport-iabg.de" Does anyone have similar-problems with this router? Traceroute Sixxs->Teredo traceroute to 2001:0:4136:e390:0:fbdc:2ae8:c03b (2001:0:4136:e390:0:fbdc:2ae8:c03b) from 2001:5c0:8fff:ffff::dd, 30 hops max, 16 byte packets 1 2001:5c0:8fff:ffff::dc (2001:5c0:8fff:ffff::dc) 107.383 ms 108.124 ms 106.654 ms 2 freenet6.hexago.com (2001:5c0:0:5::114) 107.095 ms 106.059 ms 106.386 ms 3 if-5-0-1.6bb1.mtt-montreal.ipv6.teleglobe.net (2001:5a0:300::5) 106.541 ms 106.603 ms 106.409 ms 4 if-1-0.mcore3.mtt-montreal.ipv6.teleglobe.net (2001:5a0:300:100::1) 106.592 ms 107.843 ms 106.336 ms 5 if-13-0.mcore4.nqt-newyork.ipv6.teleglobe.net (2001:5a0:300:100::2) 114.487 ms 113.379 ms 115.555 ms 6 2001:5a0:400:200::1 (2001:5a0:400:200::1) 113.91 ms 113.103 ms 113.653 ms 7 2001:5a0:600:200::1 (2001:5a0:600:200::1) 119.464 ms 119.756 ms 119.148 ms 8 2001:5a0:600:200::5 (2001:5a0:600:200::5) 119.637 ms 121.8 ms 118.875 ms 9 2001:5a0:600::5 (2001:5a0:600::5) 119.457 ms 119.633 ms 119.148 ms 10 equinix.ash.cw.net (2001:504:0:2::1273:1) 120.34 ms 120.042 ms 119.625 ms 11 so-7-0-0-dcr2.amd.cw.net (2001:5000:0:f0::2) 205.678 ms 205.652 ms 206.285 ms 12 as0-dcr1.amd.cw.net (2001:5000:0:11::1) 205.948 ms 206.094 ms 205.01 ms 13 so-0-0-0-dcr2.fra.cw.net (2001:5000:0:e::1) 219.236 ms 219.237 ms 219.56 ms 14 so-5-0-0-zcr2.muc.cw.net (2001:5000:0:63::2) 227.223 ms 226.256 ms 226.635 ms 15 m-net.muc.cw.net (2001:5001:100:f::2) 226.038 ms 226.238 ms 226.889 ms 16 mnet1-gw.teleport-iabg.de (2001:a60:0:201::2:1) 227.559 ms 227.094 ms 226.911 ms 17 vpn1.teleport-iabg.de (2001:1b10:100:3::2:1) 228.372 ms 227.172 ms 226.984 ms 18 * * * ... 30 * * *