Hi Omar,
From a cursory glance, your external DNS resolver, duckdns, doesn’t appear to be configured properly. Set up an A record to point your domain almanzel.eu to your public IP address and set up CNAME records for code, omar, etc. Next. make sure you forward your WAN HTTPS port to your Caddy instance.
You’ll find this wiki article useful Using Caddy as a reverse proxy in a home network.