I am setting up KVM host which will have multiple virtual machines visible from the outside with a similar /etc/network/interfaces config to this one  # The loopback network interfaceauto loiface lo inet loopbackauto eth0iface eth0 inet manualiface eth0 inet6 static  address 2001:0000:1004:1019::  netmask 64  post-up /sbin/ip -family inet6 route add 2001:0000:1004:10ff:ff:ff:ff:ff dev eth0  post-up /sbin/ip -family inet6 route add default via 2001:0000:1004:10ff:ff:ff:ff:ff  pre-down /sbin/ip -family inet6 route del default via 2001:0000:1004:10ff:ff:ff:ff:ff  pre-down /sbin/ip -family inet6 route del 2001:0000:1004:10ff:ff:ff:ff:ff dev eth0auto br0iface br0 inet static  address 41.100.60.25  netmask 255.255.255.0  network 41.100.60.0  broadcast 41.100.60.255  gateway 41.100.60.254  bridge_ports eth0  bridge_maxwait 12  bridge_fd 9  bridge_hello 2  bridge_maxage 12  bridge_stp off  dns-nameservers 8.8.8.8  dns-search ovh.net  post-up ip link set br0 address xx:xx:xx:xx:xx:xx  post-up ip addr add 164.123.123.123/32 dev br0 broadcast 164.123.123.123  post-down ip addr del 164.123.123.123/32 dev br0  post-up ip route add default via 41.100.60.254 dev br0  post-down ip route del default via 41.100.60.254 dev br0  post-down brctl delbr br0and both eth0 and br0 interfaces are being brought up in the end (they work) but I am seeing this when I look at the booting screen (it's not in the boot log for some reason):Waiting for network configurationWaiting upto 60 more seconds for network configurationBooting system without full network configurationAdditionally when I runifquery --stateorcat /run/network/ifstateI can see that eth0 and br0 are missinglo=loEDIT 1:By using the following commandifup br0 --no-actI got the following set of commands that are being run if you would use ifup br0run-parts  /etc/network/if-pre-up.dip addr add 41.100.60.25/255.255.255.0 broadcast 41.100.60.255    dev br0 label br0ip link set dev br0   up ip route add default via 41.100.60.254  dev br0 ip link set br0 address xx:xx:xx:xx:xx:xxip addr add 164.123.123.123/32 dev br0 broadcast 164.123.123.123ip route add default via 41.100.60.254 dev br0run-parts  /etc/network/if-up.dWhich tells me that this command gets duplicatedip route add default via 41.100.60.254 dev br0so after removing this from my configpost-up ip route add default via 41.100.60.254 dev br0post-down ip route del default via 41.100.60.254 dev br0I can see run-parts  /etc/network/if-pre-up.dip addr add 41.100.60.25/255.255.255.0 broadcast 41.100.60.255    dev br0 label br0ip link set dev br0   up ip route add default via 41.100.60.254  dev br0 ip link set br0 address xx:xx:xx:xx:xx:xxip addr add 164.123.123.123/32 dev br0 broadcast 164.123.123.123run-parts  /etc/network/if-up.dWhich solves the problem of missing br0 AFTER REBOOT when I runifquery --state# orcat /run/network/ifstatebecause I can seelo=lobr0=br0
KVM bridged interfaces not going up - inet, inet6 , bridge
networking;kvm;bridge;ipv6
I decided to remove inet6 static configuration for now so I am good after the EDIT 1.I presume that having a configuration for inet and inet6 which has two different types for e.g. static and manual is causing some command duplication when running ifup and ifdown.