All programs are required to try to use IPv6 first and Firefox will too, unless you use a REALLY old version.
The issue is with your IPv6 setup and not the browsers or HA.
Ok, but I’m not using an old version of Firefox(well, LibreWolf, so maybe it’s disabled there). But I don’t have the problem in LibreWolf, and I did have it in all my Chromium based browsers until disabling ipv6. So in practice, this does resolve the problem, which I probably am not alone in running into. I normally try not to run ipv6 for this reason, so I don’t doubt that I’m probably dropping ipv6 somewhere. Also in practice, I bet having ipv6 enabled on the network causes way more problems for most people then it does anything useful.
I am surprised that no one asked how the OP installed Home Assistant.
@ZEROX - What is the IPv4 address shown on the terminal connected to your host PC? What is the IP of your PC? What do you see when you ping homeassistant.local?
Just remember IPv6 is a requirement for Matter.
Damn this is a frustrating issue. I can curl homeassistants local address and get the HTML to pop up in my terminal, but nothing in my browser.
Just ditch mDNS reliance altogethet and configure a static IP Address on your router for your HomeAssistant server and devices and go directly to the correct IP Address from your browser on whatever machine is connected to the same LAN.
I bet he didnt put homeassistant.local in /etc/hosts file.
Static IP is done on the client. The router manages reserved IP.