Internet Connection Problems

Internet connection problems are mainly caused by the name resolution issues. Name resolution issues can be caused by miss-configuration of the TCP/IP, connection failure, router failure, or the ISP problems. Troubleshooting Internet Connection becomes common task for home users and business networks with broadband internet connection.

Home Networks

Internet connection problems for home networks are commonly related to the IP configuration of the computers, network connection problem, and router or modem problems, as well as problems at the ISP. Troubleshooting internet connection can be a difficult task for mostly users with lack of networking knowledge. How can you start troubleshooting? See also home computer networking.

Connection Problem

Firstly you need to localize what the root of the problem is. The following figure is a typical home network diagram with broadband internet connection that can be used to help the troubleshooting.

If you have more than one PC connected to the network, and only one PC that cannot connect to the internet – you can assure that you have no problems with Internet connection as general. The only problem is lying only on a single PC. The first time you need to check is the IP configuration of the PC in problem and compare it with other PCs that can connect to the Internet.

In Windows command prompt, run the ipconfig command to show the TCP/IP configuration of the PC. If the IP configuration shows that your PC using the APIPA address, then you have network connection problem to the existing network. ipconfig command will show you the IP configuration of the PC:

The above IP configuration shows the PC uses the APIPA address. In Windows system, when the computers on the network do not receive the IP address from the DHCP server or when there is no DHCP server available, the computers will use the APIPA (Automatic private IP address) in the range of 169.254.0.0 until 169.254.255.254. The home wireless routers have the DHCP server feature which is enabled by default to provide the IP configuration automatically to the computers on the network.

To troubleshoot this connection problem, you should check the network cable from the PC to the Switch or to the router (if the PC is on wired network). If the PC is on wireless network, make sure that the wireless configuration is properly setup.

Router / Modem Problem

If you find that all the computers on the network cannot access the internet, there could be problems on the router, modem, lines connection to the ISP, or probably the ISP problems. Firstly you need to check if the computers do not receive the IP address from APIPA by running the ipconfig command to make sure that the DHCP router is functional. If the IP configuration is OK, then you can test a ping command to the default gateway, and then to one of the URL in the Internet for example ping yahoo.com from command line. If the ping failed, you need to localize the problem, you should try to connect one computer direct to the modem and see if you can access the internet.

Turn off the wireless router and unplug the UTP cable from the WAN port of the router (the port with WAN or internet or WLAN labeled) and plug to the computer NIC port. If you can access the internet, then you have problem with your wireless router. Make sure that router configuration is properly setup and configured.

If you still cannot access the internet, then you have problem with the modem or problem with the local loop – line connection to the ISP. The easiest way is to make a phone call to the ISP if there is a disruption with the internet services. At this point you need your ISP assistance to resolve the problem.

By Ki Grinsing

See also:

• Networking troubleshooting – business networks.
• Understanding network problems in business networks
• Understanding many types of WAN technologies
• Sample of risk assessments
• VLAN tutorial – a best practice