As on your screenshot, you have three ethernets:
eth0, eth1, eth2 .
eth0 has an IP, so you have some config for this (ie by
eth1, eth2 is not connected to the same switch and network, to get this works it needs more settings.
You should check, that any other tools like
ifupdown not used for bringing up
eth1, eth2 and
Do not use this tools with netplan.
eth1, eth2 ifaces – remove lines with
eth1, eth2, add just one line:
iface eth1 inet manual for each.
Or rename or delete file
If you rename or delete
/etc/network/interfaces, you should add config
eth0 to netplan config.
For example, in my config I have
em1, em2 ethernets.
bond0 its together, and
br0 at the top of
br0 gets IP via DHCP.
br0 is needed to get access to network from VMs on this server.
You can remove part with
bridges and set
dhcp4: yes, dhcp6: yes to
bond0. This should also works, and
bond0 should get IP from DHCP.
Also I made a working config for
ifupdown2 (maybe because old
ifupdown can't handle ifaces dependency, but