I upgraded HA to 2020.12.1 (it now says it’s 2020.12.7) and it went smoothly except none of my Tasmota devices can resolve the server IP via the .local name (I use hass.local). Other things on the same network don’t have a problem, only the Tasmota devices, as far as I can tell. I can work around it by setting the MQTT host to an explicit IP address, but I’d rather work out why it’s broken.
The Tasmota devices are all on 8.3.1 and have been working perfectly for at least 6 months. I upgraded one to 9.2.0 to see if that would make a difference but it hasn’t fixed the problem.
Very weird.
Edit: Using terminal on the HA box shows it can’t resolve it itself, I suspect everything else might just have the address cached.
Edit2: avahi-browse on an RPi shows hass.local, both IPv4 and IPv6.
I get the impression that they have changed the .local resolution. The installation instructions now say:
On another computer, navigate to http://homeassistant.local:8123 to access Home Assistant. If you are running an older Windows version or have a stricter network configuration, you might need to access Home Assistant at http://homeassistant:8123 or http://X.X.X.X:8123 (replace X.X.X.X with your Pi’s IP address).
I found this issue. They changed from using Avahi to using systemd-resolved, but apparently if you are upgrading it doesn’t completely update your settings, although it implies that it was fixed in a later release, and I’m on 5.9, so the fix should have been there. I can’t tell from the discussion exactly where that file should be.
It’s weird that avahi-browse on another computer can see hass.local. It’s like maybe it’s a different version of the mDNS protocol, or something.