I have read and followed the "Reporting Problems" section on the Contact page and am providing the following details for this report based on the list of items stated there: It seems the PoP itself cannot ping or traceroute the remote-endpoint. Using https://noc.sixxs.net/tools/traceroute/ from sesto1 (Port80 AB) to 2001:16d8:ff00:253::2 fails. But performing the same traceroute from another PoP, e.g. AS12871 (NoC - SixXs) to 2001:16d8:ff00:253::2 is successful.