I cannot ping the PoP tunnel endpoint (no replies), but packets from their endpoint arrive locally and are answered. However, it seems as if the replies do not reach the tunnel endpoint as the status page reports 100% packet loss. Also, Jeroen has verified that no packets arrive on the box. I checked with the provider and they confirmed that the firewall ACCEPTs everything, up- and downstream, including protocol 41. I can reach the endpoint with IPv4 (tcp, icmp). If I turn the tunnel to another machine, I (well, Jeroen) can see the packets alright. So it seems like something between 213.203.238.82 (2001:6f8:900:bb7::2) and 212.224.0.188 (2001:6f8:900:bb7::1) is dropping packets in one direction only. After today's reboot of deham01, I could send exactly *one* packet (well, I got a reply to exactly one echo-request), specifically the first one I tried. I could not get another one in the hours since then.