Hi there,
i am using debian since years and lxc too. Now i have updated vom version 8 (wheezy) to 9 (stretch). So the machine is using lxc 2.x now. My virtualized container ist running almost pretty well except some confusing behaviour.
If i boot the maschine, the container starts up and the host shows 3 virtual network devices per ifconfig. I configured just one virtual device.
If i stop the container and lxc with “/etc/init.d/lxc stop” all 3 veth-devices disapear. If i now start only the container with “lxc-start -n container” it appears just one veth-device like i want.
Has anybody an idea how to solve that behavior. I don´t want do use a self-build hack with scripts to automate 
Thanks a lot
rsa