ok I tried to add those two in my Caddyfile:

ac.ghodawalaaman.duckdns.org {
	reverse_proxy http://localhost:4000/ {
		header_up X-Forwarded-Host {host}
		header_up X-Forwarded-For {host}
		header_up X-Real-IP {host}
	}
}

here is the output of a request.

2025/04/16 15:52:17.005	WARN	http.handlers.reverse_proxy	aborting with incomplete response	{"upstream": "localhost:4000", "duration": 0.000995717, "request": {"remote_ip": "103.250.137.61", "remote_port": "19389", "client_ip": "103.250.137.61", "proto": "HTTP/3.0", "method": "GET", "host": "ac.ghodawalaaman.duckdns.org", "uri": "/static/vite_dist/assets/Roboto-Light-DHTugVNA.woff2", "headers": {"User-Agent": ["Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0"], "Sec-Fetch-Dest": ["font"], "Accept-Encoding": ["identity"], "Cookie": ["REDACTED"], "Sec-Fetch-Mode": ["cors"], "Accept": ["application/font-woff2;q=1.0,application/font-woff;q=0.9,*/*;q=0.8"], "Accept-Language": ["en-US,en;q=0.5"], "X-Forwarded-For": ["ac.ghodawalaaman.duckdns.org"], "X-Real-Ip": ["ac.ghodawalaaman.duckdns.org"], "Sec-Fetch-Site": ["same-origin"], "Alt-Used": ["ac.ghodawalaaman.duckdns.org"], "X-Forwarded-Host": ["ac.ghodawalaaman.duckdns.org"], "X-Forwarded-Proto": ["https"], "Referer": ["https://ac.ghodawalaaman.duckdns.org/static/vite_dist/assets/Layout-Cv860oWs.css"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h3", "server_name": "ac.ghodawalaaman.duckdns.org"}}, "error": "writing: H3_REQUEST_CANCELLED"}

I also tried this but it didn’t work either:

ac.ghodawalaaman.duckdns.org {
    	log {
    	    output file ./azuracast.log
    	    format json
    	}
	reverse_proxy http://localhost:4000/ {
		header_up X-Forwarded-For {request.remote}
		header_up X-Real-IP {request.remote}
	}
}

here is the azuracast.log: 0x0.st/8fd7.bin

I am still very confused why it’s not working…