If a computer is unable to connect to a network or see other computers on a network, it is necessary to troubleshoot the network. There are multiple reasons that cause problems in network. People should know about it as it will help them to resolve the issues easily without assistance of professionals.Basic Causes

See if:

• Network card is attached or not
• Wrong software settings or bad network card drivers’ attachment
• Interaction of firewall preventing computer to see each other
• Wrong or incompatible instalment of hardware
• Network connection related issues

Solution:

Due to the large variety of network configurations, operating systems, setup, etc, all of the below information may apply to your network or operating system. If your computer has connection to a large network or a company and you are not the administrator of the network, it is recommended to allow the network administrator to resolve this issue. While single computer users can follow the below recommendations when they are contacted to the network as a administrator.

Verify connections / LEDs

It is better to check that the network cable is connected to the computer properly. you also need to check the connection of the network cable, get surety that whether the LEDs on the network are illuminated or not. For example, a network card with a solid green LED or light indicates that the card is either connected or receiving a signal. Remember that when the green light is flashing, it is an indication of data being sent or received.

If the card does not show any light or the red or orange light on this card, it is possible that either the card is not connected or the card is not getting signals from the network.

If you are on a small or local network and have the capability of checking a hub or switch, verify that the cables are properly connected and the hub or switch has power.

Adapter resources:

Ensure that if there is a new network card being installed into the computer that the card’s resources are properly set and are conflicting with any hardware in the computer.

Adapter functionality:

Verify that the network card is capable of pinging or seeing itself by using the ping command. Windows users can ping the computer from a DOS prompt where you need to go to the run, type cmd and click ok, it will open the ms dos while. UNIX or Linux users can ping the computer from the shell.

Protocol:

Verify that the correct protocols are installed on the computer. Most networks today will utilize TCP/IP, but may also utilize or require IPX/SPX and NetBEUI.

Firewall:

If your computer network utilizes a firewall, ensure that all ports required are open. If possible, close the firewall software program or disconnect the computer from the firewall to ensure it is not causing the problem.

Additional time:

In some cases it may take a computer some additional time to detect or see the network. If after booting computer you are unable to see the network, give the computer 2-3 minutes to detect the network. Windows users may also want to try pressing the F5 (refresh) key when in Network Neighbourhood network connections have problems.