Ethernet, WiFi on Bond Bridge Setup Help


New Member
Dec 5, 2021
I have 2 physical interfaces, enp43s0 (ethernet) & wlp0s20f3 (wifi).

I also have two virtual bridges; vmbr0 (used by proxmox for web ui access), and vmbr1 (for all vms to use, connected as local NAT on subnet).

Most of the time, I am connected through WiFi, but I'd like to have a fallback to ethernet whenever I am docked at home.

For this, I have setup a bond bridge (bond0), but I am not able to access internet on VMs or locally (on proxmox).

This is my /etc/network/interfaces config.

auto lo
iface lo inet loopback

auto enp43s0
allow-hotplug enp43s0
iface enp43s0 inet manual
    bond-master bond0
    bond-primary enp43s0
    bond-mode active-backup

allow-bond0 wlp0s20f3
allow-hotplug wlp0s20f3
iface wlp0s20f3 inet dhcp
    bond-master bond0
    bond-primary enp43s0
    bond-mode active-backup
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

auto bond0
iface bond0 inet manual
    bond-slaves none
    bond-primary enp43s0
    bond-mode active-backup

auto vmbr0
iface vmbr0 inet static
    bridge-ports none
    bridge-stp off
    bridge-fd 0
auto vmbr1
iface vmbr1 inet static
    bridge-ports none
    bridge -stp off
    bridge-fd 0

    post-up   echo 1 > /proc/sys/net/ipv4/ip_forward
    post-up   iptables -t nat -A POSTROUTING -s -o wlp0s20f3 -j MASQUERADE
    post-down iptables -t nat -D POSTROUTING -s -o wlp0s20f3 -j MASQUERADE

I did some troubleshooting here & there for a few hours but I wasn't able to figure it out. I also tried changing the interface on the last 2 lines to bond0 but that didn't work as well.

Sorry if this config looks dumb, getting back into networking after a few years and I am rusty (learnt it during but that was it).
Last edited:


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