[ubuntu] qemu/kvm bridge not selectable in guest configuration

Hallo,

in the attachment you can see my host network adapters (lo, enp0s31f6, virbr0,virbr0-nic,anbox0) in the upper left terminal window, the virtual network of qemu in the lower left corner (virt-manager), the nm-connection-editor in the lower middle and the NIC configuration possibilities of the Lubuntu guest system.
As you can see
1. in the guest configuration the virbr0 devices are not selectable
2. the virbr0-nic and anabox0 are not listed in the virt-manager window
3. virbr0-nic and anabox are also not listet in the nm-connection-editor

Who can explain this?

My main goal is to set up my guests in a way that they get the ip from the DHCP my host is connected with. They should be in the same network as my host.
I have tried to create a bridge by myself with nm-connection-editor and it worked, but after rebooting the host there was neither the new crated bridge nor does the host NIC get connected/started. I do not understand this and need help. Network setup is not my daily job and is not well known.

Regards

Frank

Attached Images

• Bildschirmfoto vom 2020-07-15 22-21-07.jpg (88.3 KB)