KVM | debian | building a bridge

You did set up a kvm and have one physical interface with IP 192.168.100.121, i.e. eno1? To get a bridge tune your /etc/network/interfaces like this: That means: Yout establish a virtual bridge br0 with ip 192.168.100.121 and your physical interface eno1 is docked on the inner side of this bridge. YOURLAN << br0WITH192.168.100.121<<>>YOURPHYSICALeno1