hello Greg, thanks for the answer, now I am not so alone ;-) this Problem with the third NIC in a KVM Client is from Update to Update stronger. I mean on start the Installation "CentOS 7.0" we don't have this Problem! without NetworkManager is run, on my system, I can't start the third Network- Card, I have always a LSB Error on the KVM-Clients ?? So now I found a workaround for my Problem :-(. (What are changed in the Network Configuration) I set up the first and second NIC to "hostdev" (hardware) this is running also before the update and set “NM_CONTROLLED=no” to this NIC's. The third is a Bridge controlled Interface now is running with NetworkManager as a static Interface with "PEERDNS=no" so I have my resolv.conf is not always change and NetworkManager don't create a new Interface with a DHCP config ?? Why Network Manager do that with 7.6, I can't say but I am not happy witzh this update :-(. -------------------------------------------------------------------------- Gunter, You are surely not alone, there are many on this list that have a keen understanding of things with a lot of experience that provide excellent assistance. I consider myself to be a sponge absorbing everything I can, compared to most contributors on this list :) The migration from 7.5 to 7.6 has been somewhat painful for me too, but the work the Centos team does in providing this service for us is outstanding. Most of the time these upgrades are just a 'blink' and the machines that upgrade have no problems. However, I do have to admonish myself from time to time with the encouragement of 'it is time to learn', and I have a lot that I can learn. Good Luck!!!!! Greg