Ping on ipv6.google.com, no replies in Debian

Hello Forum,

I have a Debian 10.13 and a Windows machine behind an OpenWRT router. I added a Hurricane Electric Tunnel to my network to access IPv6 addresses, because my Internet provider delivers only a IPv4 address. Now I want to test my IPv6 configuration with ping. The internet tips suggest pinging ipv6.google.com. In windows all works fine, but under Debian I get no replays. In Debian the name is resolved to 2a00:1450:4005:800::200e correctly, so no DNS problem!

On the router, I put a TCPDump on the lan interface: tcpdump -q -i eth0.1 icmp6

If I do the windows ping (ping ipv6.google.com), I can see:
Quote:

19:13:13.566513 IP6 1234:5678:9999::240 > ham11s07-in-x0e.1e100.net: ICMP6, echo request, seq 761, length 40 19:13:13.612127 IP6 ham11s07-in-x0e.1e100.net > 1234:5678:9999::240: ICMP6, echo reply, seq 761, length 40 19:13:14.567659 IP6 1234:5678:9999::240 > ham11s07-in-x0e.1e100.net: ICMP6, echo request, seq 762, length 40 19:13:14.605271 IP6 ham11s07-in-x0e.1e100.net > 1234:5678:9999::240: ICMP6, echo reply, seq 762, length 40

But the linux ping (ping6 -s 32 ipv6.google.com) gives no replies? (I set the payload to 32+8 to make it the same size as the windows ping)
Quote:

19:13:40.474225 IP6 1234:5678:9999::249 > ham11s07-in-x0e.1e100.net: ICMP6, echo request, seq 1, length 40 19:13:41.479673 IP6 1234:5678:9999::249 > ham11s07-in-x0e.1e100.net: ICMP6, echo request, seq 2, length 40 19:13:42.502166 IP6 1234:5678:9999::249 > ham11s07-in-x0e.1e100.net: ICMP6, echo request, seq 3, length 40

If I ping the newspaper www.welt.de I get ping IPv6 replies on both machines. What does it mean? The Google server knows somehow which is a Linux ping and decides not to answer in this case, or do I still have an error in my configuration? Is it the high sequence number?

Can you ping6 ipv6.google.com with your Debian machine?

Thanks

Peter