🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026

📖 ~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

Primary interface disappears after reboot, causing loss of SSH access and service connectivity.

Environment & Reproduction

Observed after installing a new kernel where vendor NIC module is missing or not rebuilt.

Root Cause Analysis

Kernel-module mismatch prevents NIC driver initialization and udev cannot create expected network device name.

Quick Triage

Check lspci visibility, dmesg module failures, and whether previous kernel still exposes the interface.

Step-by-Step Diagnosis

Audit module dependencies, inspect DKMS build status, and confirm netplan references existing interface names.

Illustrative mockup for ubuntu-18-04-lts — nic_missing_problem
Network interface absent from ip link output — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Install matching driver package, rebuild DKMS module, refresh initramfs, and apply corrected netplan mapping.

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Illustrative mockup for ubuntu-18-04-lts — nic_driver_restored
Driver loaded and interface restored — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Boot prior kernel, use generic driver fallback, or pin known-good kernel until vendor patch is validated.

Verification & Acceptance Criteria

Interface appears consistently, obtains expected IP, and connectivity tests pass across reboot cycles.

Rollback Plan

Revert kernel and driver package changes if updated module introduces packet loss or instability.

Prevention & Hardening

Pre-stage tested drivers for new kernels and include out-of-band access for remote maintenance windows.

Link predictable interface rename issues, DHCP timeout problems, and matching Ubuntu networking tutorial.

Related tutorial: View the step-by-step tutorial for Ubuntu 18.04 LTS.

View all Ubuntu 18.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Consult netplan docs, Ubuntu kernel module guidance, and NIC vendor release notes.

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