Ubuntu 20.04 VPN Connection Drops Network Access

📖 ~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

Activating VPN causes loss of internet or local network connectivity.

Environment & Reproduction

Connected VPN status but no browsing, DNS, or internal resource access.

Root Cause Analysis

Ubuntu 20.04 using OpenVPN or WireGuard via NetworkManager.

Quick Triage

Default route takeover, broken DNS push, or MTU mismatch.

Step-by-Step Diagnosis

Inspect ip route, resolvectl output, and VPN profile route settings.

Solution – Primary Fix

Configure split tunneling, correct DNS domains, and tune MTU for tunnel path.

Solution – Alternative Approaches

Public internet and target private resources remain reachable while connected.

Verification & Acceptance Criteria

Version control VPN profile settings and test after endpoint changes.

Rollback Plan

Escalate when VPN gateway policy pushes conflicting enterprise routes.

Prevention & Hardening

Disable auto-default-route on VPN and revert to known working profile.

Related Errors & Cross-Refs

NetworkManager VPN docs and OpenVPN/WireGuard routing guidance.

Related tutorial: View the step-by-step tutorial for Ubuntu 20.04 LTS.

View all Ubuntu 20.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

A full-tunnel profile intentionally routes all traffic through VPN.