Hmm, it looked like
ip6tables -A INPUT -p icmpv6 --icmpv6-type packet-too-big -j ACCEPT
ip6tables -A OUTPUT -p icmpv6 --icmpv6-type packet-too-big -j ACCEPT
ip6tables -A FORWARD -p icmpv6 --icmpv6-type packet-too-big -j ACCEPT
fixed it, but now the IPv6-troubles are back again. However, this time only with Google-services and it looks like I'm not the only one:
http://forums.whirlpool.net.au/forum-replies.cfm?t=2360847 , IPv6 test-websites don't indicate any problems this time.
http://test-ipv6.com/ : 10/10
http://ipv6-test.com/ : 17/20, "Your router or firewall is filtering ICMPv6 messages sent to your computer. An IPv6 host that cannot receive ICMP messages may encounter problems like some web pages loading partially or not at all." and "Get a reverse DNS record"
ESS is blocking ping-replies, that shouldn't cause any problems and disabling the firewall doesn't solve the connection issue.
Is there any way to troubleshoot problems connecting to a website through IPv6? As soon as I disable IPv6 or manually enter the IPv4 address (apparently Firefox doesn't automatically falls back on IPv4 with Google), I can access Google without problems and just like with the others from that link, the problem is intermittent. Sometimes it works, but mostly doesn't.
Someone from that link mentioned something about routing issues.
It happens with both Google.com and Google.nl and a traceroute doesn't seem to show anything out of the ordinary.
C:\Users\Bart>tracert google.nl
Traceren van de route naar google.nl [2a00:1450:4013:c01::5e]
via maximaal 30 hops:
1 <1 ms <1 ms 1 ms 2001:*:*:*::1
2 8 ms 7 ms 8 ms bartgrefte-1.tunnel.tserv11.ams1.ipv6.he.net [2001:*:*:*::1]
3 12 ms 4 ms 18 ms v213.core1.ams1.he.net [2001:470:0:7d::1]
4 5 ms 5 ms 6 ms core1.ams.net.google.com [2001:7f8:1::a501:5169:2]
5 5 ms 5 ms 5 ms 2001:4860::1:0:4b3
6 5 ms 5 ms 5 ms 2001:4860::8:0:51a0
7 8 ms 14 ms 8 ms 2001:4860::8:0:517a
8 8 ms 8 ms 8 ms 2001:4860::2:0:8651
9 * * * Time-out bij opdracht.
10 8 ms 8 ms 8 ms ea-in-x5e.1e100.net [2a00:1450:4013:c01::5e]
De trace is voltooid.
C:\Users\Bart>tracert google.com
Traceren van de route naar google.com [2a00:1450:4013:c01::8a]
via maximaal 30 hops:
1 <1 ms <1 ms <1 ms 2001:*:*:*::1
2 8 ms 8 ms 8 ms bartgrefte-1.tunnel.tserv11.ams1.ipv6.he.net [2001:*:*:*::1]
3 7 ms 5 ms 4 ms v213.core1.ams1.he.net [2001:470:0:7d::1]
4 5 ms 5 ms 5 ms core1.ams.net.google.com [2001:7f8:1::a501:5169:2]
5 5 ms 5 ms 6 ms 2001:4860::1:0:4b3
6 5 ms 5 ms 5 ms 2001:4860::8:0:519f
7 12 ms 9 ms 18 ms 2001:4860::8:0:517a
8 8 ms 8 ms 8 ms 2001:4860::2:0:8652
9 * * * Time-out bij opdracht.
10 8 ms 8 ms 8 ms ea-in-x8a.1e100.net [2a00:1450:4013:c01::8a]
De trace is voltooid.
C:\Users\Bart>
edit: This problem is now reported on the Dutch IT-forum Tweakers.net as well.