Situation: There is ipv4 only router in network and every computer is connected to it (wifi or cable). Server with ipv4 and ipv6 is connected to this router as well. Server has configured tunnelbrokers 6to4 tunnel and radvd. Clients in network has right prefix and can ping each other. But they can't ping to internet until they ping Server (the one with tunnel). I found somewhere that it's icmp problem, but I couldn't find solution. Is it problem that there is ipv4 only router? server and client runs linux router runs dd-wrt without ipv6 support :( Ping try: standa@standa-laptop:~$ ping6 ipv6.google.com PING ipv6.google.com(2a00:1450:8007::69) 56 data bytes ^C --- ipv6.google.com ping statistics --- 29 packets transmitted, 0 received, 100% packet loss, time 28223ms standa@standa-laptop:~$ ping6 2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478 PING 2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478(2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478) 56 data bytes 64 bytes from 2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478: icmp_seq=1 ttl=64 time=3.55 ms 64 bytes from 2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478: icmp_seq=2 ttl=64 time=0.311 ms 64 bytes from 2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478: icmp_seq=3 ttl=64 time=0.269 ms 64 bytes from 2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478: icmp_seq=4 ttl=64 time=0.292 ms ^C --- 2001:470:XXXX:XXXX:21c:c0ff:fe2b:6478 ping statistics --- 4 packets transmitted, 4 received, 0% packet loss, time 3000ms rtt min/avg/max/mdev = 0.269/1.107/3.559/1.415 ms standa@standa-laptop:~$ ping6 ipv6.google.com PING ipv6.google.com(2a00:1450:8007::69) 56 data bytes 64 bytes from 2a00:1450:8007::69: icmp_seq=1 ttl=57 time=20.7 ms 64 bytes from 2a00:1450:8007::69: icmp_seq=2 ttl=57 time=20.2 ms 64 bytes from 2a00:1450:8007::69: icmp_seq=3 ttl=57 time=23.4 ms ^C --- ipv6.google.com ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2001ms rtt min/avg/max/mdev = 20.267/21.479/23.413/1.392 ms