I can fetch the header of websites via IPv6 but not the webpage, why?

Ez Egy ezegyemailcim123 at gmail.com
Tue Jan 21 21:30:03 CET 2014

The solution was setting the MTU to 1480 in radvd in the router:

option AdvLinkMTU       1480
# option AdvLinkMTU     1452

On Mon, Jan 20, 2014 at 5:22 PM, Ez Egy <ezegyemailcim123 at gmail.com> wrote:

> As I said:
> 1) "I have a native IPv6 connection on my Desktop behind my router." -> So
> there is no tunnel. Only native IPv6 that the Hungarian telekom.hu gives.
> 2) We will try out setting manually the MSS to 1392, hopefully that could
> be a good workaround.
> 3) We will try out the site: http://netalyzr.icsi.berkeley.edu/
> I will post the status here later, Thanks!
> On Mon, Jan 20, 2014 at 11:59 AM, Tore Anderson <tore at fud.no> wrote:
>> * Ez mail
>> > Since I have no fr**king clue what could the problem be, I'm trying on
>> > this list :)
>> I concur 100% with Erik's assessment that this in all likelihood is a
>> PMTUD problem, specifically in the web_server->your_desktop direction.
>> I'd just like to add that the fact that you see it happening to several
>> independent websites that are known to be operated by competent staff,
>> and that the problem comes and goes, further indicates that it is due to
>> rate-limiting of ICMPv6 PTB replies from your tunnel broker's tunneling
>> router/server.
>> The ICSI Netalyzr (http://netalyzr.icsi.berkeley.edu/) will give you
>> very useful debugging output from the outside point of view. You might
>> have to run it a few times to to reveal the MTU blackhole though, due to
>> the problem's intermittent nature.
>> As Erik mentions, lowering the TCP MSS will likely work around the
>> problem. You can probably do this by having the RAs your router emits to
>> the LAN advertise an MTU of 1452 to match your tunnel (which in turn
>> should make your desktop default to a TCP MSS of 1392), and/or have your
>> router rewrite ("clamp") the MSS value in TCP packets it forwards
>> to/from the tunnel to 1392.
>> Or, even better, get rid of the tunneling crap and get native IPv6. This
>> is a very common problem for IPv6 tunnels. As a web site operator I
>> would actually prefer it if people stayed IPv4-only until their ISP
>> could provide them with properly supported IPv6 connectivity. Oh well...
>> Tore
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