Basic network troubleshooting.

Issue

Basic network troubleshooting.

Cause

A network may not work because of any of the below reasons.

1. Network or router connection issue card not connected properly.
2. Bad network card drivers or software settings.
3. Firewall preventing computers from seeing each other.
4. Connection related issues.
5. Bad network hardware.

Solution

Because of the variety of network configurations, operating systems, setup, etc. not all of the below information may apply to your network or operating system.

Note: We cannot assist you with network problems due to unknown passwords or unknown ISP settings.

Adapter resources

Verify that the network adapter is properly installed and detected by the computer with no conflicts. If you're using Microsoft Windows check in Device Manager and verify there are no errors and "Network adapters" is present with each network adapter installed in the computer listed, similar to the example on the right.

If conflicts exist or the network adapter is being detected as an Other device. The network card has not been properly installed in the computer. Try letting Windows re-detect and install the Network card by removing the network adapter and any other conflict devices from Device Manager and then rebooting the computer. If Windows re-detects the card but does not find the drivers, download the network adapter drivers from the computer manufacturer or the network card manufacturer.

Verify connections

Wired Network

If this is a wired network, verify that the network cable is properly connected and make sure the LEDs next to the network jack are properly illuminated. For example, a network card with a solid green LED or light usually indicates that the card is either connected or receiving a signal. If the green light is flashing, this is an indication of data being sent or received. In the picture to the right, is an example of LAN port with two LED indicators next to the RJ-45 port. With this port, one LED will light up if connected properly and the other will flash when transmitting data.

If there are no lights or the lights are orange or red the card may be bad, not connected properly, or that the card is not receiving a signal from the network. If you are on a small or local network and have the capability of checking a hub, switch, or router verify that the cables are properly connected and that it has power. If after checking the connections the LED indicators appear bad, the network adapter, port, or cable may be defective.

Wireless Network

If you're using a laptop with a wireless network make sure if the laptop has a Wi-Fi button that it is turned on. Many laptops will have a Wi-Fi button that allows the wireless network to be turned on and off. In the picture to the right, is an example of a Wi-Fi button that is currently enabled.

If the Wi-Fi button is turned on, make sure you're connecting to the correct Wi-Fi hotspot by right-clicking on the Network icon in the Windows notification area and clicking "Connect to a network". Usually, the network with the strongest connection (the most bars) will be your wireless router.

Finally, when connecting to most wireless networks you will need to enter the proper SSID (password) in order to connect to the network. If the incorrect SSID has been entered you will be denied access to the network.

Adapter functionality

Verify that the network card is capable of pinging itself by using the ping command. Windows users can ping the computer from a Windows command line. Unix and Linux users can ping from the shell.

To ping the card or the localhost, type either

ping 127.0.0.1

or

ping localhost

Doing either of the above commands should get replies from the network card. If you receive an error or if the transmission fails the network card is not physically installed into the computer correctly, has the incorrect drivers, or that the card is bad.

Connect to the router

If all of the above steps have been checked and your network has a router, make sure the computer can connect to the router by performing the below commands.

Determine the routers address

Using the ipconfig command (or ifconfig command for Linux) determine the router's address by looking at the Gateway address. Below are the steps for Microsoft Windows users, Linux users can substitute ipconfig for ifconfig.

1. Open the Windows command line.
2. From the command prompt type ipconfig and press enter. This command should give you an output similar to the below example.

Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : computerhope.com.
IP Address. . . . . . . . . . . . : 192.168.1.103
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1

The Default Gateway is the address of your router. Most home routers will have a gateway address that starts with 192.168 like the address shown above. Assuming your gateway address is 192.168.1.1 attempt to ping the router to see if it can send and receive information by running the below command.

ping 192.168.1.1

If you get replies back from the router, the connection between your router and computer are good, and you can skip to the next step.

If you do not receive any replies back from the router either the router is not setup properly or your connection between the router and the computer are not correct. Reset your router to make sure it is not a problem with your router by following the below steps.

1. Turn off the power to the computer and leave it off.
2. Unplug the power to your router and cable modem or DSL modem.
3. Leave the power cables disconnected for 10-15 seconds and then plug in your modem and then your router again.
4. Finally, turn on your computer again and repeat this step to see if you can ping your router.

If you're using a wireless network and have followed all the above steps and still are unable to ping the router try turning off the computer again and connect the computer to the router using a cable instead of trying to connect using wireless. If a wire does also not work connect the manufacturer of the router for additional support or replacement.

Firewall

If your computer network utilizes a firewall, make sure all required ports required are open, especially port 80, which is the HTTP port. If possible, disable the firewall software program or disconnect the computer from the firewall to make sure it is not causing the network problems.

Internet is not working

If you're able to ping the router, but are still unable to connect to the Internet, either your router is improperly configured or the ISP is having issues.

Note: Some ISPs such as Comcast require special software be installed. Make sure any software included with your Modem or other hardware has been installed on at least one computer if you are setting up a new Internet connection.

If your Internet has been working but recently stopped working, give it a few minutes to make sure it is not a temporary outage. If after waiting a few minutes, you still have problems and you have not disconnected the power to your router and modem already follow the below steps.

1. Turn off the power to the computer and leave it off.
2. Unplug the power to your router and cable modem or DSL modem.
3. Leave the power cables disconnected for 10-15 seconds and then plug in your modem and then your router again.
4. Finally, turn on your computer again and repeat this step to see if you can ping your router.

If after following the above steps the Internet is still not working, open the Windows command line and run the below command.

ping google.com

Running the above command should get a reply from Google. If you get a reply, this is an indication that the Internet is working, but you may be encountering a problem with the Internet browser you are using to browse the Internet. Try an alternative browser such as Firefox or Chrome.

If you're getting no reply from Google, your router or modem is not reaching the Internet. If you have a router, make sure your router has DHCP enabled and that the WAN or Gateway address is the proper ISP address.

Finally, after verifying all of the above settings if your Internet is still not working we suggest contacting the ISP to make sure it is not a problem on their end and to assist you further with any special configurations that may not be mentioned in this document.

Additional troubleshooting

Another method of determining network issues is to use the tracert command if you are a Windows user or the traceroute command if you are a Linux or Unix variant user. This command will give you an overview of each of the devices (routers) a packet travels (hops) over a network and can give you an idea of where a problem exists in your network or outside of your network.

To use this command you must be at the command line and type one of the below commands depending on your operating system.

tracert google.com

or

traceroute google.com

If run successfully you should begin to see each hop between the computer and network devices. When the connection fails, determine what device is causing the issue by reviewing the traceroute listing.

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Filed Under: COMPUTER TRICKS, NETWORKING on