Running FAI in QEMU/KVM: Need a working configuration to install clients

[c.monty at web.de]

Hello!
I want to deploy SLES on several clients.
Due to restrictions (we are only running OS SLES or RHEL) I have installed QEMU/KVM on a host and created a guest (VM) based on Debian 9 with FAI.

I would need support for some configuration steps, in particular regarding the network setup.
All clients are in the same network as the host where QEMU/KVM is running.

On this host I created 2 virtual networks:
default
virbr0
192.168.100.0/24
DHCP range: 192.168.100.10-254
NAT on br0

internal
virbr1
192.168.33.0/24
DHCP disabled
Isolated network, internal and host routing only

The VM running FAI has two NICs:
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:31:dd:59 brd ff:ff:ff:ff:ff:ff
    inet 192.168.100.52/24 brd 192.168.100.255 scope global ens3
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe31:dd59/64 scope link
       valid_lft forever preferred_lft forever
3: ens8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 52:54:00:9e:23:26 brd ff:ff:ff:ff:ff:ff
    inet 192.168.33.250/25 brd 192.168.33.255 scope global ens8
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe9e:2326/64 scope link
       valid_lft forever preferred_lft forever

The DHCP daemon in FAI is configured to listen on ens8 only.

Question:
What is the correct network configuration on host and guest?
How can I ensure that other clients can be installed with FAI?

THX