Docker 29 Broke My VPS. Claude Code Found Two Bugs I Didn’t Know Existed.

I opened my SaaS dashboard and got this: Web server is down - Error code 521 You → Cloudflare → myapp.example.com Browser Dallas Host ✅ Working ✅ Working ❌ Error TL;DR: A routine Docker update silently broke two things on my production server. My reverse proxy couldn't discover services anymore, and a port conflict appeared out of nowhere. Claude Code diagnosed both problems over SSH from my local machine, without being installed on the server. Total time from "it's down" to HTTP 200: 25 minutes. When your production server decides to take an unscheduled vacation. First reflex : the domain. I pulled up my registrar to check if the domain was still active. It was. Then I tried another subdomain on the same domain. Loaded fine. So the domain isnt the problem. Second thought : n8n crashed. It happens. Docker containers die, databases run out of memory, the usual suspects. Im already mentally preparing for a docker restart and a cup of coffee. Third thought: wait. If the other subdomain wo