My Caddyfile doesn't work

I deploying an web server on an embedded device. I did a web application stored in /var/www/app/assets where I have my html pages. I need to serve it to devices connected (by wifi). I installed caddy on the embedded device but I have issues with the "Caddyfile". when I try to access to the IP address of the embedded device, I get "404 not found". Here is my Caddyfile:

http://192.168.1.10 {
    root /var/www/app/assets
}

Thank you