Cloudflare · infra · fg-0208

App on port 3000 or 5000 times out once its DNS record is proxied through Cloudflare

Connection timed out to https://app.example.com:3000

Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100

Cause

Proxied records only accept traffic on a fixed port list: 80, 8080, 8880, 2052, 2082, 2086, 2095 for HTTP and 443, 2053, 2083, 2087, 2096, 8443 for HTTPS. Anything else needs DNS only or Spectrum.

Fix

Serve the app on a supported port behind a reverse proxy, or set the record to DNS only.

Apply

server {
  listen 443 ssl;
  server_name app.example.com;
  location / { proxy_pass http://127.0.0.1:3000; }
}

Affects: Cloudflare proxied (orange cloud) records on all plans; arbitrary ports need Spectrum (all ports on Enterprise)

Sources

Have your agent know this before it fails

claude mcp add --transport http footgun https://getfootgun.com/api/mcp