… actually I did get it to work with your config in NGINX Proxy Manager, I just put the entire locations in the Advanced section of the Proxy Host in Nginx Proxy Manager and then it came back online and was able to pass the traffic correctly. I was trying to just put the individual nginx variables at first. This is what I put in my Advanced section and it starting working again. Thanks for the quick confirmation that it works and for providing your example!
location / {
set $upstream_app homeassistant;
set $upstream_port 8123;
set $upstream_proto http;
proxy_pass http://192.168.1.104:8123;
}
location /api/websocket {
set $upstream_app homeassistant;
set $upstream_port 8123;
set $upstream_proto http;
proxy_pass http://192.168.1.104:8123;
proxy_set_header Host $host;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}