Network Interface & Bridge Change

To change the default bridge in Proxmox, you need to edit the /etc/network/interfaces file on the node you want to change. Here's an example of how to change the default bridge from vmbr0 to vmbr1 or change the physical interface fro eth0 to eth1:

1. Log in to the node as root.
2. Open the /etc/network/interfaces file in a text editor, such as nano or vim.
3. Locate the section that defines the default bridge, which typically looks like this:

Sample Config

#Pyhsical interfaces
iface eth0 inet manual

iface eth1 inet manual

#Bridge interfaces
auto vmbr0
iface vmbr0 inet static
        address 192.168.1.100
        netmask 255.255.255.0
        gateway 192.168.1.1
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0

Change Physical Interface

Change the eth0 to eth1 and update the bridge_ports line to reflect the new eth interface.

auto vmbr1
iface vmbr1 inet static
        address 192.168.1.100
        netmask 255.255.255.0
        gateway 192.168.1.1
        bridge_ports eth1
        bridge_stp off
        bridge_fd 0

Change Bridge Interface

Change the vmbr0 to vmbr1 and update the bridge_ports(if needed) line to reflect the new bridge interface.

auto vmbr1
iface vmbr1 inet static
        address 192.168.1.100
        netmask 255.255.255.0
        gateway 192.168.1.1
        bridge_ports eth1
        bridge_stp off
        bridge_fd 0

Post Update

1. Save the changes to the /etc/network/interfaces file.
2. Restart the networking service to apply the changes:

   systemctl restart networking
   

You can also restart the node itself for the changes to take affect!

Note: Be careful when editing the /etc/network/interfaces file, as incorrect changes can cause network connectivity issues. It's a good idea to make a backup of the file before making changes.