At some version (can't remember the exact version) Docker introduced network ID registration within the container itself. For this reason when Docker starts (after starting the array), the rc.docker script reconnects the networks using their previously registered IDs and allow containers to re-use them.
The "network not found" error implies the container is started before the network is ready/created.
It could be there is a difference between autostart of containers or manual start, hence my earlier question.
Ps. I also like to get a clarification on the statement "shutdown dockers". Is this stopping the docker service or stopping the containers from running?