Troubleshooting a Network

The following sections list a series of common networking problems along with solutions that can usually set things right again.

Network Software Setup

Problem

Duplicate computer names.

Solution

Make sure that every computer on the network has a unique name. Otherwise, you'll get an error message when you reboot the workstations with networking cables attached. (You can change the computer name from the System applet of the Control Panel, although you must restart the system for it to be effective.)

Problem

Different workgroup names.

Solution

Make sure every computer that's supposed to be working together has the same workgroup name. The Windows 9x/NT Network Neighborhood and Windows Me/2000/XP My Network Places icons display computers by workgroup name. Different workgroup names actually create different workgroups, and you'd need to access them by browsing via Entire Network. You can also make this change from the System applet, although it too requires rebooting the system to become effective.

Problem

Shared resources are not available.

Solution

Make sure that shared resources have been set for any servers on your network (including peer servers on Windows 9x). If you can't share a resource through Windows Explorer on the peer server, ensure that File and Printer Sharing has been installed.

Problem

Network doesn't work after making changes.

Solution

Did you reboot? Any change in the Network icon in Windows 9x/Me Control Panel requires a system reboot!

Did you log in? Any network resources can't be accessed unless you log in when prompted. You can use Start, Shutdown, and Close All Programs and Logon As a New User with Windows 9x/Me to recover quickly from a failure to log on.

Networks in Use

Problem

A user can't access any shared resources (but others can).

Solution

First, have the user log off and log back on. Pressing Cancel or Esc instead of logging in would keep a user off the network.

Next, check cable connections at the server and workstation. Loose terminators or BNC T-connectors can cause trouble for all workstations on a Thinnet cable segment. A loose or disconnected RJ-45 cable affects only the computer (or hub) using it. If a Category 5 UTP cable seems to be connected tightly but the user still can't get on the network, check the cable with a cable tester or replace the cable.

Problem

Wrong access level.

Solution

If you save your passwords in a password cache, entering the read-only password instead of the full-access password limits your access with peer servers. Try unsharing the resource and try to reshare it, or have the user of that peer server set up new full-access and read-only passwords. Alternatively, don't use password caching by unchecking the Save Password box when you log on to a shared resource. With a client/server network with user lists and rights, check with your network administrator because she will need to change the rights for you.

TCP/IP

Problem

Incorrect settings in Network Properties.

Solution

Get the correct TCP/IP settings from the administrator and enter them; restart the PC if you're using Windows 9x. Windows 2000 and newer do not require the PC to be restarted after changing TCP/IP settings.

Problem

Can't keep connection running in Dial-Up Networking.

Solution

You might have the wrong version of PPP running; change the server type in Properties under Dial-Up Networking, not Networks.

Problem

Message about duplicate IP addressescan't connect to anything.

Solution

Duplicate IP addresses disable both TCP/IP and NetBEUI networking. Internet sharing products such as ICS, third-party sharing programs, and routers are usually configured to assign IP addresses automatically to avoid duplication. If some computers on a network have fixed IP addresses and others have dynamically assigned IP addresses, conflicts could occur. The entire network should use dynamic IP addressing (DHCP) or each computer should be assigned a unique IP address.

Problem

No error messagecan't connect to Internet or other computers.

Solution

Check the router, switch, or hub used to connect the computers to each other and the Internet. It needs to be powered, and the data cables must be properly connected between it and each PC (and between the Internet connection and the switch or hub, if applicable).

If your network uses DHCP to dynamically assign IP addresses and the router has lost power or connection, users won't have valid IP addresses. Restart the router, and have all users log off and shut down. When they restart their systems, they should be able to obtain valid IP addresses and connect with each other.