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[slyronit]

I set up a Tunnel between my router and HE successfully, with my /64 subnet being allocated to my LAN segment. Now, my PCs (All Windows 10) can ping IPv6 domains without issues (So DNS is fine), but cannot open IPV6 websites at all. I tried going as low as 1400 for MTU (update: Down to 1280) no joy.

Packet captures show

1. Ping to ipv6.google.com succeeding
2. When opening ipv6.google.com, the TCP three way handshake succeeds, then after the HTTP GET request, re-transmissions start, after which the connection is reset by the server

Has anyone seen this happen? I don't think there's anything special with my setup.

PS: The board wouldn't let me add attachments, so here's a OneDrive link
https://1drv.ms/u/s!AoqVc_KYCVoWjKBcPSQbNnZXQSch5A

[UpTide]

I am having the EXACT same problem right now. Did you ever come up with a solution? Does anyone have a solution?

[maikthiel1977]

I can confirm this problem with Windows 8.1 Pro (Update 1) behind a Fritz!Box 7490 using DTAG (Deutsche Telekom AG) infrastructure. Tried PoPs in Frankfurt, Duesseldorf and Amsterdam but this made no difference. Setting MTU to minimum of 1280 bytes on both ends of the tunnel neither improves the situation. Some TCP packages are transmitted but after a few seconds I encounter TCP RSTs and the communication hangs. New requests made some seconds later may work or not, depending on magic. I especially noted this problem using maps.google.com or en.wikipedia.org.

My solution is a dirty hack: I use a linux PC behind the Fritz!Box to connect to a virtual server (administered by me) somewhere on the internet via OpenVPN where another HE tunnel terminates. I'm tunneling IPv6 packages from my home network via OpenVPN to the vServer and from there via HE tunnel to the internet. Works, but it is a quite complicated setup if you just want to use IPv6 connecting via an ISP that doesn't support it (Thank you, congstar!  )

Maik

[JasonLeschnik]

I'm having the same issues and I traced it back to a blog article with a similar set of issues: https://ttlexpired.co.uk/2016/02/12/ipv6-tunnel-and-failing-tcp-sessions/

[maikthiel1977]

I can confirm this problem with Windows 8.1 Pro (Update 1) behind a Fritz!Box 7490 using DTAG (Deutsche Telekom AG) infrastructure. Tried PoPs in Frankfurt, Duesseldorf and Amsterdam but this made no difference. Setting MTU to minimum of 1280 bytes on both ends of the tunnel neither improves the situation. Some TCP packages are transmitted but after a few seconds I encounter TCP RSTs and the communication hangs. New requests made some seconds later may work or not, depending on magic. I especially noted this problem using maps.google.com or en.wikipedia.org. ...

Just for information: the problem has obviously disappeared after an update to Fritz!OS 6.90 on the box, it now works flawlessly for more than two weeks.

Maik

[rotanid]

it works for me - partly.
only devices connected via LAN cable don't have the problem anymore with Fritz!OS 6.90.

devices connected via WIFI still have these problems unfortunately :-(