📖 ~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

Interface is up and profile is active, but external hosts are unreachable.

Environment & Reproduction

Wrong default route, stale DNS, or profile-level IP settings in NetworkManager.

Root Cause Analysis

Run: nmcli device status, ip route, and resolvectl status.

Quick Triage

Test gateway reachability and DNS separately to isolate routing from name resolution issues.

Step-by-Step Diagnosis

Capture active profile parameters before making network changes.

Illustrative mockup for rhel-9 — rhel9-nmcli-state-01.webp
nmcli shows connected profile with incorrect gateway or DNS — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Capture updated IPv4 settings and route metrics after fix.

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Illustrative mockup for rhel-9 — rhel9-nmcli-fix-ipv4-02.webp
Applying corrected IPv4 gateway and DNS using nmcli — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Adjust profile: sudo nmcli con mod ipv4.gateway ipv4.dns “1.1.1.1 8.8.8.8”.

Verification & Acceptance Criteria

Reconnect: sudo nmcli con down && sudo nmcli con up .

Rollback Plan

If needed, set autoconnect and route metric to prefer correct interface.

Prevention & Hardening

Confirm with ping -c 3 8.8.8.8 and ping -c 3 redhat.com.

Standardize nmcli profile templates and avoid manual edits to transient resolver files.

Related tutorial: View the step-by-step tutorial for rhel-9.

View all rhel-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Restore previous connection profile backup and reactivate it via nmcli con up.

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