mDNS discovery on new VLAN, how does it work?

I’m a long time user of HASS and new to ESPHome, coming from Tasmota.

My HASS install is on an Ubuntu VM which has interfaces on my main network (eth0) and my IoT VLAN (eth0.200) where all my Tasmota / ESPHome devices are.

If I configure my new ESPHome devices on the main network, HASS finds them automatically, presumably using mDNS discovery.

If I then switch to my IoT network, auto discovery in HASS doesn’t work. However, on the HASS VM I can see the ESPHome devices broadcasting on the IoT VLAN, using avahi-browse --all:

+ eth0.200 IPv4 pilot                                         _esphomelib._tcp     local
+ eth0.200 IPv4 officemeaco                                   _esphomelib._tcp     local
+ eth0.200 IPv4 sonoff-dogs                                   _esphomelib._tcp     local

They just don’t appear in HASS. So, it makes me think that HASS is either filtering them out, or using some entirely different method of discovery.

Note that I can manually add each ESPHome device using it’s IP, but I really want auto discovery to work!

Would anyone have any advice, please?

Under Settings → System → Network → Network adapter
make sure to enable any additional network interface you need.

Wonderful, that did it! Thanks!