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Network Issue Debugging Methodology

An evidence-driven, falsification-first playbook for tracking down network, streaming and protocol bugs where the obvious cause is usually wrong.

Dev & CodingAdvanced★ 1,323⑂ 212AI score 8/10Last updated: Aug 8, 2026

What it does

  • Triggers on symptoms like ECONNRESET, HTTP/2 RST_STREAM INTERNAL_ERROR, stalled SSE/long-polling streams, "fails after exactly N seconds", CDN/proxy/CGNAT idle timeouts, TLS certificate-verification errors, and client-side proxy/VPN/TUN misrouting — and forces an evidence → falsifier → decisive experiment sequence instead of guesswork.
  • Ships an 8-step investigation checklist: scope the symptom, verify the premise, gather per-hop evidence, frame ≥3 hypotheses with explicit refuters and target layer boundaries, run a layered-isolation experiment, add env-gated instrumentation, counter-review, fix and re-verify, then document the wrong turns.
  • Includes a reverse-proxy log-reading table (duration, bytes_read, Content-Length, status=0) that separates Cloudflare 524/522 caused by body upload time from genuine backend processing timeouts.
  • Catalogs 15 cognitive traps: circumstantial convergence, field-semantic confusion, green health checks that only certify one plane, CNAME rules overriding explicit PROXY rules, banners/OUIs mistaken for device identity, and more.

Who it's for

  • Backend engineers, SREs and platform/infra folks who debug production incidents themselves
  • Teams running multi-hop stacks (CDN → LB → reverse proxy → app → upstream)
  • Anyone operating SSE/streaming APIs or large-body POST endpoints
  • Leads who want consistent, teachable incident write-ups

Example uses

  1. "Our SSE stream dies at exactly 130s" → Claude designs three paths differing by one hop (via CDN, --resolve straight to origin, server loopback) and pins the idle timeout to a specific layer.
  2. "6 MB upload returns Cloudflare 524" → inspect Caddy JSON logs; bytes_read < Content-Length with status=0 proves an upload timeout, not a slow backend.
  3. "One site returns ERR_CONNECTION_CLOSED on my laptop only" → walk the proxy/TUN checklist: fake 198.18.x.x DNS answers, route interface, hostname-vs-IP through the proxy, and CNAME-suffix DIRECT rules beating an explicit PROXY rule.

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/daymade/claude-code-skills/HEAD/debugging-network-issues/SKILL.md

What I want: (describe your task here)

If Claude can't open the link, open it yourself and paste the contents instead.

↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)
  1. Download the ZIP with the button below.
  2. In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
  3. Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.
↓ Download ZIP
Install in Claude Code

Let Claude do it — paste this into Claude Code

Install the skill I found on Claude Skill Mart.
Copy the debugging-network-issues folder from the GitHub repo daymade/claude-code-skills into my ~/.claude/skills/debugging-network-issues/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone https://github.com/daymade/claude-code-skills.git /tmp/ccs && mkdir -p ~/.claude/skills && cp -r /tmp/ccs/debugging-network-issues ~/.claude/skills/

⚠ This is a third-party skill. Check the source repository before installing.

  1. Open a terminal.
  2. Clone the repository: git clone https://github.com/daymade/claude-code-skills.git
  3. Create the skills folder if needed: mkdir -p ~/.claude/skills
  4. Copy this skill: cp -r claude-code-skills/debugging-network-issues ~/.claude/skills/
  5. Verify the bundled references/ docs (case studies, instrumentation patterns, packet-capture recipes) came along: ls ~/.claude/skills/debugging-network-issues
  6. Restart Claude Code and paste a real symptom (e.g. "HTTP/2 INTERNAL_ERROR after 130.9s") to confirm the skill activates.
  7. Substitute the example container names and paths (Caddy, <new-api-container>, etc.) with your own infrastructure before running any commands.
View source on GitHub ↗License: MIT