I suppose, choosing the heartbeat variant might be the problem. At least that was the problem for me, why I couldn't earn credits with my freetzed Fritz.Box 7170 when I first started using IPv6 via Sixxs. It seems that the Fritz.Box does only allow proto41 traffic if it is initiated from the internal network, like it does with TCP-Traffic. I could earn credits when I kept the tunnel connection working by generating IPv6 traffic once in a while (a single ping packet every other minute or so). But the correct solution for me to this problem was, to switch over to AYIAY tunnel which works like a charm for over 18 months now, but also has the disadvantage, that it costs some credits first.

Thanks for your answer, Jacco. I do not see any "last alive" timestamp. Neither on the homescreen or on the tunnel details. But I recognize a unique "loss package" peak near by 50%. The other graphs shows no data (0%/NaN line). The only timestamp I see is the "created" timestamp on the tunnel details.

Hello, I had similar Problems about two weeks ago. Basically, you have to run aiccu on a host behind your Fritzbox for a week until you get the missing ISK to request a subnet. See the thread in the General-Forum: https://www.sixxs.net/forum/?msg=general-3458297 Best regards, Dirk