I am experiencing connectivity issues to a particular provider "Strato" in Germany since they upgraded their WEB and POP services to IPv6 on the IPv6-day. I have tested two different SixXS tunnels (the one I am using at home and this one we have at work for testing) with the same connectivity results. The ping -6 to one of the affected webpages e.g. www.net-select.de (2a01:238:20a:202:1090::144) works without problems but the page often (not always) does not deliver data back to the initial HTTP get request. TCP handshake passed ok before. The page (and the POP connection) work flawlessly with IPv4. Other IPv6 pages such as www.heise.de don't show similar issues. Even the main Strato site 2a01:238:20a:202:6660:0:198:33 is always working. Web pages like testipv6.com show no issues. The tunnel is continuously working fine. When using other tunnel mechanims (e.g. 6to4 over an AVM Fritzbox) the affected WEB pages and POP connections are reachable without problems. Strato claims they have tested with different IPv6 devices and canot find any problem. Here are the connection details for the tunnel at work: User: JAQ1-SIXXS Tunnel: T56305 POP: decgn01 We are using an Astaro Firewall that terminates and routes our network to the tunnel endpoint. The tunnel passes a NAT device to the Kabel Baden-Wrtemberg network. 1 <1 ms <1 ms <1 ms fw.net-select.de [10.210.2.254] 2 4 ms * * iGateway [109.192.254.88] 3 8 ms 8 ms 7 ms 172.30.20.41 4 9 ms 10 ms 8 ms HSI-KBW-078-042-040-041.hsi3.kabel-badenwuerttem berg.de [78.42.40.41] 5 12 ms 12 ms 11 ms ae2.FRA-M1.ip-bb.kabel-badenwuerttemberg.de [78. 42.40.11] 6 11 ms 15 ms 16 ms rtdecix2-g00.netcologne.de [80.81.193.212] 7 16 ms 16 ms 15 ms core-pg1-t41.netcologne.de [89.1.16.9] 8 16 ms 18 ms 15 ms core-eup2-t41.netcologne.de [87.79.16.205] 9 15 ms 15 ms 19 ms sixxs-pop1.netcologne.net [78.35.24.124] I have done a lot of testing and tracing but cannot find the problem here on my side. It looks as if packets are missing on the way bach from these servers when the connection runs though the SixXS tunnels. Thanks for helping. I would have traces in my end if required.