Affected versions: Debian 11

πŸ“– ~1 min read

Table of contents
  1. Symptom & Impact
  2. Environment & Reproduction
  3. Root Cause Analysis
  4. Quick Triage
  5. Step-by-Step Diagnosis
  6. Solution – Primary Fix
  7. Solution – Alternative Approaches
  8. Verification & Acceptance Criteria
  9. Rollback Plan
  10. Prevention & Hardening
  11. Related Errors & Cross-Refs
  12. References & Further Reading

Symptom & Impact

Intermittent connectivity occurs as traffic prefers broken IPv6 paths.

Environment & Reproduction

Seen after gateway changes or inconsistent router advertisements.

Root Cause Analysis

Incorrect IPv6 routes or RA handling create invalid next-hop selection.

Quick Triage

Compare IPv4 versus IPv6 path behavior and active route tables.

Step-by-Step Diagnosis

Inspect interface state, RA parameters, and route priorities over time.

Illustrative mockup for debian-11 β€” terminal_or_shell
IPv6 route and neighbor diagnostics β€” Illustrative mockup β€” Progressive Robot

Solution – Primary Fix

Correct IPv6 gateway and route policy, then reload network configuration.

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Illustrative mockup for debian-11 β€” log_or_config
Network interface and routing config evidence β€” Illustrative mockup β€” Progressive Robot

Solution – Alternative Approaches

Temporarily disable IPv6 on affected interface during active incident.

Verification & Acceptance Criteria

Connectivity stabilizes and packet loss disappears on dual-stack tests.

Rollback Plan

Restore prior network profile if new routing policy causes regressions.

Prevention & Hardening

Continuously monitor route changes and enforce network config baselines.

Related to DNS AAAA preference and firewall rule asymmetry.

Related tutorial: View the step-by-step tutorial for debian-11.

View all debian-11 tutorials on the Tutorials Hub β†’

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Debian IPv6 network configuration and operational troubleshooting docs.

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