Was hoping someone might be able to help with a bridging issue on Debian 11... I can't get it to work and I've been tearing my hair out all day! The bridged interface will not get an IP via DHCP and if you configure it statically it's not accessible.
What I'm trying to do is simple and something I've done many times before. So to prove I'm not going mad, I've created 2 brand new virtual machines with identical hardware configurations. One has a fresh installation of Debian 10 (10.13.0) and one with Debian 11 (11.5.0)
Immediately after the OS installation is finished, I log on to each as root and run the command
apt-get install bridge-utils
Completes as expected on both.
On both, I then open /etc/network/interfaces and set it to:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
source /etc/network/interfaces.d/*
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
#allow-hotplug eth0
#iface eth0 inet dhcp
iface eth0 inet manual
iface eth1 inet manual
iface br0 inet dhcp
bridge_ports eth0 eth1
I then reboot both and do:
ifup br0
Which then works fine on Debian 10:
But on Debian 11, DHCP fails:
If you configure the bridge statically then it also works on Debian 10, but not on Debian 11 (the interface isn't accessible and cannot ping in or out)
I can use Debian 10, but I hate not knowing why I can't get something to work, especially after I've spent all day completely baffled!
I'm sure there's some simple change that requires an extra step, but for the life of me, I've not been able to find it! So any help is very much appreciated.
Edit to add:
Doesn't work on a fresh installation of Debian 11.0.0 (rather than 11.5.0) either. So it's got to be something fundamental that's changed between version 10 and 11.
