How to Fix Network Issues on Ubuntu 24.04 [2025 Latest Guide]

By 佐川 直弘 | Naohiro Sagawa (運営者)

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1. Introduction

Ubuntu is widely used for its stability and flexibility. However, in the latest version, Ubuntu 24.04 LTS, users have reported network issues that prevent proper connectivity. This article provides a detailed guide on troubleshooting and resolving these network connection problems.

This guide is intended for beginners and intermediate users. It offers useful solutions for situations where Wi-Fi or wired LAN is not recognized, or when a DNS error prevents internet access.

2. Network Issues in Ubuntu 24.04: Causes and Overview

Common Network Connection Issues

Network connection issues in Ubuntu can arise from various causes. Below are some common examples:

• Wi-Fi not connecting
  The system may fail to find an access point, or the connection may not succeed even with the correct password.
• Wired LAN not recognized
  The system may not detect the network connection even when the cable is properly plugged in.
• Internet inaccessible due to DNS errors
  Even if an IP address is obtained, websites may not load.

Main Causes

Network connection issues can be categorized into the following causes:

1. Hardware issues
   Physical defects in the network card or Wi-Fi adapter.
2. Configuration errors or Netplan misconfiguration
   Incorrect or missing settings in configuration files can cause connection failures.
3. Driver compatibility issues
   Some drivers may not be compatible with the latest Ubuntu version.
4. Software conflicts
   Multiple network management tools interfering with each other.

3. Basic Troubleshooting Steps

Simple Checks

Start by eliminating physical causes with the following checks:

• Check cables and physical connections
  For wired LAN, ensure the cable is properly connected. For Wi-Fi, confirm that the access point is operational.
• Check Wi-Fi switch status
  Some laptops have a physical switch to enable or disable Wi-Fi. Ensure that it is turned on.

Basic Terminal Commands for Diagnosis

Next, use terminal commands to check the network status.

1. ip address command
   Check the current network interfaces and their statuses.

   ip address

Example output:

   3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
       link/ether 00:1a:2b:3c:4d:5e brd ff:ff:ff:ff:ff:ff
       inet 192.168.1.100/24 brd 192.168.1.255 scope global dynamic wlan0

If the interface is not in the UP state, it may be disabled.

2. ping command
   Test network connectivity.

   ping -c 4 8.8.8.8

If there is no response, the system is unable to connect to external networks.

Restarting and Resetting Network Services

If the problem persists, try the following steps:

1. Restart the system
   Rebooting often resolves many network issues.

   sudo reboot

2. Restart network services
   Restarting the Network Manager can reset connections.

   sudo systemctl restart NetworkManager

4. Specific Issues and Solutions

4.1 If the Device is Not Recognized

If the network interface is not recognized, check its status.

Checking the Interface

1. Use the ip link command
   Check whether the network device is detected.

   ip link

If eth0 (wired LAN) or wlan0 (Wi-Fi) does not appear, the device may not be properly recognized.

2. Check and install necessary drivers
   If the driver is missing, reinstall it using the following commands.

   lspci | grep -i network

Based on the output, search for and install the appropriate driver.
Example:

   sudo apt install linux-modules-extra-$(uname -r)
   sudo reboot

Hardware Testing

• If using a USB Wi-Fi adapter, try a different USB port or check for hardware defects.

4.2 Netplan Configuration Errors

Ubuntu 24.04 uses Netplan as its default network management tool. Misconfigured Netplan settings can cause connectivity issues.

Checking the Netplan Configuration

1. The configuration files are located in the /etc/netplan/ directory. View them with the following command:

   sudo nano /etc/netplan/01-netcfg.yaml

Example configuration:

   network:
     version: 2
     renderer: networkd
     ethernets:
       eth0:
         dhcp4: true

2. After saving the changes, apply the Netplan configuration.

   sudo netplan apply

Common Errors and Fixes

• YAML Formatting Errors
  Incorrect spacing or indentation can cause errors. Use an online YAML validator to check the format.
• Errors when applying settings
  Try testing the configuration before applying.

  sudo netplan try

5. Case Studies: Solutions Based on Real Scenarios

5.1 Wi-Fi Not Recognized on Ubuntu 24.04

Issue:
After installing Ubuntu 24.04, many users report that Wi-Fi is not recognized and cannot connect to a network. The Wi-Fi interface may not be displayed, and access points may not be detected.

Solutions

1. Install Wi-Fi drivers
   If the Wi-Fi adapter is not functioning correctly, installing the necessary drivers may resolve the issue.

   sudo apt update
   sudo apt install linux-firmware
   sudo reboot

After rebooting, check if Wi-Fi is recognized.

2. Restart network services
   If drivers are installed correctly but Wi-Fi is still not working, restart the network services.

   sudo systemctl restart NetworkManager

3. Enable Wi-Fi interface manually
   If the Wi-Fi interface is disabled, activate it using the following command.

   sudo ip link set wlan0 up

4. Disable power management settings
   Some Wi-Fi adapters experience connectivity issues due to power management settings. Disable it using the following command.

   sudo iwconfig wlan0 power off

5.2 Wired LAN Suddenly Stops Working

Issue:
In some cases, wired LAN stops working unexpectedly, preventing internet access. This often occurs after system updates or kernel changes.

Solutions

1. Check cables and ports
   Verify the physical connection by trying a different cable or port.
2. Fix Netplan settings
   Check and modify the wired LAN configuration file as needed.

   sudo nano /etc/netplan/01-netcfg.yaml

Example configuration:

   network:
     version: 2
     renderer: networkd
     ethernets:
       eth0:
         dhcp4: true

After making changes, apply Netplan.

   sudo netplan apply

3. Reinstall network drivers
   If a recent kernel update caused the issue, reinstall the necessary network modules.

   sudo apt install --reinstall linux-modules-extra-$(uname -r)
   sudo reboot

4. Check system logs
   If the problem persists, check the system logs for errors.

   sudo dmesg | grep -i eth

Based on the error messages, apply additional fixes as necessary.

6. Network Configuration Differences: Comparison with Ubuntu 20.04 and 22.04

Ubuntu 24.04 introduces improvements to network management, making some configuration methods different from previous versions. This section explains key differences and important considerations for migration.

Netplan Enhancements

Since Ubuntu 20.04, Netplan has been the default network configuration tool. However, in 24.04, the following changes have been made:

1. Simplified Default Configuration
   In 24.04, the initial Netplan configuration is more streamlined. In many cases, renderer: NetworkManager is used by default.

DNS Configuration Changes

Ubuntu 24.04 has improved the default DNS settings across the system, bringing these notable changes:

• Enhanced systemd-resolved
  DNS caching is enabled by default.
• To clear or restart DNS, use:

   sudo systemctl restart systemd-resolved

7. Frequently Asked Questions (FAQ)

Q1: My Wi-Fi connects briefly but disconnects soon after. Why?

Cause:
Power management settings might be causing the adapter to enter sleep mode.

Solution:

1. Check the current power management settings.

   iwconfig wlan0

If it shows Power Management: on, disable it.

2. Disable power management.

   sudo iwconfig wlan0 power off

Q2: I can ping an IP address, but websites don’t load. Why?

Cause:
DNS settings might be incorrect.

Solution:

1. Check the current DNS settings.

   cat /etc/resolv.conf

If the output is empty, DNS is not set.

2. Temporarily set Google Public DNS.

   sudo nano /etc/resolv.conf

Modify the file as follows:

   nameserver 8.8.8.8
   nameserver 8.8.4.4

8. Conclusion

Network connection issues in Ubuntu 24.04 can arise from various causes. However, by following basic troubleshooting steps, most issues can be resolved. This guide helps you:

• Quickly identify and fix network problems.
• Understand Netplan settings and DNS configuration.
• Optimize network settings in virtual environments.

If the solutions here do not resolve your issue, consider checking the official Ubuntu documentation or forums like Ask Ubuntu for further support.

We hope this guide helps you achieve a smooth and stable network experience on Ubuntu!

References

Netplan | Canonical Netplan

Backend-agnostic network configuration in YAML.…