Hello @ all With the rebuilding of my Server from Debian 9 to Debian 10, I also switch from Virtual Box to Libvirt/KVM. Due to new requirements for the VMs, now I have an actual problem, which unfortunately I can not solve. The problem has already been discussed in the German Debian-Forum ... unfortunately also without success. The facts: - ISP = Dual Stack with daily separation - Host and VM = Debian 10 - The VMs are via macvtap-device regular LAN-Clients - IPv4 = DHCP and NAT by DSL-Router - IPv6 = GUA via RA and SLAAC (2003::/3) - IPv4 works fine in the VM - IPv6 (NDP, RA, SLAAC) works basically also fine in the VM The existing problem in the VM: - MAC-Based GUA (2000::/3) is ok, both inbound and outbound - Outbound traffic via the second GUA (PE-Based) is filtered apparently, but not via packetfiltering, I don't know where. There are no error messages. On the part of the kernel in the VM and the IPv6-stack, everything looks completely ok, no error messages, except that Outbound-Traffic by the PE-Address is quietly blocked. The MAC- Based IPv6 works unchanged and without error as before. My questions: 1. Is there a special setting for the VM, to allow the use of Privacy Extensions for IPv6 unlimited? 2. Or is that possibly even a known and at the moment unsolved problem? 3. Or is this a intended limitation of virtualization? Can anyone help me with a solution or a hint? Thank you.