System diagnosis

A system issue is happening. Diagnose and fix it on a Debian/Ubuntu Linux machine using a systematic, hypothesis-driven loop. Gather evidence before changing anything; confirm before applying a fix.

Diagnostic steps

1. Describe the problem: what is happening, and when did it start?
2. Gather information:
   • System logs: journalctl -xe
   • Specific service logs: systemctl status <service> and journalctl -u <service> -xe
   • Resource usage: top, htop, df -h
   • Network: ip addr, ping, ss -tlnp
3. Identify patterns: is it consistent or intermittent?
4. Check recent changes: what changed before the issue appeared?
5. Research: look for known issues.
6. Test hypotheses: verify the likely cause before acting.
7. Implement the fix: apply the solution.
8. Verify: confirm the issue is resolved (systemctl is-active <service>, reproduce the original symptom).