There’s definitely a problem with the nginx config based on that command.
I looked into the configs further and it appears there were recent updates to the default nginx configs in swag in the September release, so that could be causing some conflicts with the original post and my config I gave you earlier.
If you are going to use the homeassistant.subdomain.conf.sample file, nginx configs are spread across multiple files (default.conf, nginx.conf, proxy.conf, ssl.conf, and homeassistant.subdomain.conf) and a problem with any of these will cause an issue. Because it becomes difficult to track the config across multiple files, I followed the advice in this guide, Nginx Reverse Proxy Set Up Guide – Docker and my whole config is in the default.conf file, and I just make changes there, and don’t use the homeassistant.subdomain.conf file.
If you don’t go the route in that guide to put everything in one config, and since I don’t know where the issue is on your config, what you can try doing is restore the default configs. To do that, backup everything, stop swag, and delete any of the changed files in the volume (default.conf, nginx.conf, proxy.conf, ssl.conf, and homeassistant.subdomain.conf). Restarting swag will then restore these config files back to the default ones. Then try to change the name of homeassistant.subdmain.conf.sample to drop the .sample, and see if that works.
You also need to replace the line
set $upstream_app homeassistant;
With
set $upstream_app 192.168.XX.XXX;
Using the ip of the machine running home assistant. Since Home Assistant is in host networking mode, it can’t be reached on the docker network by container name and you need to spell out the ip