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 <ezegyemailcim...@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 <t...@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 >> > >