Customers outside the network cannot load the site: every external request times out while nginx reports healthy.
Stage 4 of 4 in Network Response Ladder.
Synthetic checks from three regions time out after ten seconds instead of getting an error page.
The web team points out that curl on the host itself works perfectly.
The migration replaced the host's saved firewall ruleset with the new subnet's template.
The fix is yours to find: hints, the recovery checks and the debrief unlock inside the incident.
The alert fires and the clock starts. Read the page and the briefing.
Work in a simulated shell with realistic output: logs, configs, services.
Change the system the way you would in production. Hints are there if you get stuck.
Automated checks verify the recovery, then the debrief explains what happened.
Free, instant, and it works on your phone. No signup: start as a guest and save your progress later.