Why does Ubuntu have network connection but cannot access the Internet?

The reasons why ubuntu has a network connection but cannot access the Internet: 1. DNS configuration problem; 2. Proxy server setting problem; 3. Network firewall setting problem; 4. Router or modem setting problem; 5. Network driver problem ; 6. Network configuration file problems; 7. Other problems. Detailed introduction: 1. DNS configuration problem. Make sure the network connection is normal. You can test whether the network connection is normal by entering "ping 8.8.8.8" in the terminal. If a normal result is returned, the network connection is stable, etc.

The operating system of this tutorial: windows10 system, DELL G3 computer.

When Ubuntu has a network connection but cannot access the Internet, it may be due to a variety of reasons. The following are some possible causes and corresponding solutions:

1. DNS configuration problem:

• Make sure the network connection is normal. You can test whether the network connection is normal by entering ping 8.8.8.8 in the terminal. If normal results are returned, the network connection is stable.

• Check whether the DNS configuration is correct. Enter cat /etc/resolv.conf in the terminal to view the DNS configuration. Make sure the correct DNS server address is included in the configuration.

• If the DNS configuration is incorrect, you can modify the DNS server address by editing the /etc/resolv.conf file. For example, you can add Google's public DNS server addresses 8.8.8.8 and 8.8.4.4.

2. Proxy server setting problem:

• If your network connection is through a proxy server, make sure The proxy settings are correct. Check whether the IP address and port number of the proxy server are correctly configured.

• If necessary, proxy settings can be modified by editing the network configuration file. The specific steps may vary depending on the Ubuntu version, but the relevant settings can usually be found and modified in network configuration files (such as /etc/network/interfaces or /etc/netplan/).

3. Network firewall settings problem:

• Check whether the network firewall settings are correct. In Ubuntu, you can use the ufw command to manage firewall rules. Make sure the required ports and protocols are allowed through the firewall.

• If you are using a UFW firewall, you can enter the following command to open the web ports (such as 80 and 443):

bash`sudo ufw allow 80/tcpsudo ufw allow 443/tcp`

4. Router or modem setting issues:

• Check whether the router or modem settings are correct. Make sure the router or modem is properly connected to the Internet and that it is configured correctly.

• If you are using a router, you can try restarting the router or checking the router's settings to make sure it is properly connected to the Internet.

5. Network driver problem:

• Check whether the network driver is working properly. Enter lspci | grep -i ethernet in the terminal to check whether any network card is correctly recognized. If the network card does not show up or appears yellow or red, there may be a problem with the network driver.

• Try updating or reinstalling the network driver to resolve the issue. In Ubuntu, network drivers can be updated and installed using the sudo apt-get update and sudo apt-get install network-manager commands.

6. Network configuration file problem:

• Check whether the network configuration file is configured correctly. Ubuntu's network configuration files are usually located in the /etc/network/interfaces or /etc/netplan/ directory. Check that the configuration in these files is correct and try restarting the network service to apply the changes.

7. Other problems:

• If none of the above methods solve the problem, it may be caused by other problems. For example, system updates, software conflicts, or other unknown factors may cause network connection issues. In this case, it is recommended to check Ubuntu's official documentation or seek community support for help solving the problem.

Please note that the above solutions may vary depending on Ubuntu version and specific environment. When trying to resolve a problem, be sure to back up important data and understand the risks and considerations before taking any action.

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