What To Do When . . .Your LAN Isn’t Working

If you asked somebody how to successfully do a jigsaw puzzle, they’d probably tell you match whatever you can, and good luck. Think that’s a good analogy to troubleshooting LANs (local-area networks)? We’d need to throw in half a dozen or more puzzles, together. The field is filled with software and hardware designed to build and maintain networks, similar in generalities but often very unalike in detail. This makes offering problem solving adice that’s applicable to all LANs very challenging. But there are some difficulties that repeat between networks, and some conditions that hold true for all because they involve Windows XP or good basic maintenance practices. So while we can’t guarantee that this article will make your network problem free, we think it provides a good chance of fixing things before you get into the rocket science of unique network complexities.

Problem: I’ve got a wireless network, and my connection is spotty at best.
Solution: Wireless connections can be tricky. Sometimes they can work over relatively long distances but fail across the room. If your clients are within signal range of your router, begin by looking for other electronic devices that can generate electronic interference. Microwaves are frequent culprits; others are additional wireless units, such as wireless speakers, Bluetooth devices, and cordless phones. Even wireless mice, garage door remotes, and brick walls have been known to cause problems. In short, overlook nothing and test everything if your wireless LAN experiences periodic performance drops. Found the problem? Just because interference is present, that doesn’t mean it’s omnipresent. Try moving your router. Raise it several feet, or put it in an area away from other electronic gear. Even a difference of a few inches may make the difference between a good, solid connection and a poor, spotty one. Or lacking that, try moving your wireless clients away from interference causing devices. Another solution is to upgrade the antenna on your router, or add a range extender. Some antennas are removable, and you can purchase more powerful models.

Problem: We had a brief blackout, and I had to reset my main computer. When it came back up, though, I was unable to access the Web, and my personal LAN can’t, either.
Solution: It sounds as though your computer has temporarily lost its IP (Internet Protocol) address and can’t identify itself to your ISP (Internet service provider). Several conditions can cause this problem. The first thing to try is a normal Windows reboot, as the OS (operating system) doesn’t respond well to sudden interruptions in service and may not have come back correctly. Shut down your PC and manually turn off your cable/DSL (Digital Subscriber Line) modem and router. Wait about a minute, then start up your computer and turn those devices back on. Wait a couple minutes and see if the restart was sufficient to reset your IP address. If not, click Start and Run, then type ipconfig/ release in the Open field of the Run dialog box and press ENTER or click OK. This sends a request to your provider’s DHCP (Dynamic Host Configuration Protocol) server to blank or unconfigure your IP address. Wait a few seconds and then click Start and Run again, only this time type ipconfig/renew and click OK. The DHCP server will now attempt to establish a new IP address for your computer. You may need to reboot at the end of this process, but either way you should once more be able to communicate with your provider.

Problem: My networked computers have suddenly stopped communicating with one another. Are there any possibilities I can look into before getting help from someone more technically savvy than myself?
Solution: Sometimes the most straight forward solution is the right one, and because it’s so obvious it goes overlooked. So start by doing the obvious: Check the cables that connect your router or hub with your PCs. While unconnected cables should show up in your Network Communications window or as a faulty device in your Device Manager, a partially seated or damaged cable may not. Don’t just check visually. Make sure the cables are well-seated by hand. If you feel a lot of give, the plug or its corresponding port may be poorly secured. Try reconnecting to a different port, then try using a different network cable. Make sure that all devices are properly powered up. It’s not unheard of for power cords to come loose as a result of movement or the addition or subtraction of other power cords to or from an outlet, or perhaps someone “borrowed” the power outlet your small network depends upon. If this reveals nothing, check out the status of all your devices’ LEDs. Green is usually good, but orange, red, or anything that flickers between orange or red and another color isn’t.

Problem: I’m trying to print a document from a computer on my network other than the one it’s connected to and it won’t work. Everything else works fine.
Solution: This sounds like an issue with a Windows networking component called File And Printer Sharing For Microsoft Networks. Is it installed and enabled? Some people deliberately leave it disabled because of fears that it permits breaches to security. This is inaccurate, because you’d have to fulfill a number of other important conditions to leave your computer open to general access. Make sure that the files you want to print can be shared; use Windows Explorer to locate them, then right click each one and select Properties in the pop-up menu that appears. In each file’s Properties dialog box, click the Sharing tab and make sure the Local Sharing And Security option isn’t checked. Instead, select the Network Sharing And Security checkbox. Finally, note at the bottom of the Sharing tab whether your firewall is configured to permit network sharing of that file or folder. Windows Firewall has an option to disallow this because it assumes you might be accessing your computer at times in less secure locations, such as airports, offices, and cars. If you’re using a third-party firewall, you’ll want to make sure it’s set to allow network sharing, as well. Also note that some files and folders, such as program files and Windows system folders, cannot be shared.

Problem: One of the computers on my network repeatedly gets the message “The list of servers for this workgroup is not currently available” when I attempt to open its Network Neighborhood window.
Solution: It sounds like your Computer Browser service is disabled. Click Start, right-click My Computer, then click Manage in the context menu. In the Computer Management window that appears, click the plus sign (+) next to Services And Applications in the left panel, and then double-click Services. Scan the list of services in the right panel to find Computer Browser. If it lists Stopped in the status field, double-click the Computer Browser entry and click the Start button in the Service Status portion of the General tab in the dialog box that appears. You’ll also want to make sure Automatic is selected in the Startup Type drop-down menu and click OK. Some users who want more memory for applications disable these types of services because they tie up system memory whether they’re currently in use or not. If you share the system in question with other users, you might want to see if one of them has stored a profile that automatically disables Computer Browser upon startup. Click Start, Shut Down, and Restart, then watch to see if Windows offers you a choice of user profiles instead of simply starting up.

Problem: When I try renewing a DHCP lease it fails. I get this message: “An error occurred while renewing interface [NAME]. The system cannot find the file specified.”
Solution: This can happen when the DHCP Client service has been stopped and your IP address is showing up as 0.0.0.0. To fix this, click Start and right-click My Computer, then click Manage. In the Computer Management window, click the plus sign next to Services And Applications in the left panel, then double-click Services. Double click DHCP Client in the right panel, then click the Start button in the General tab if the Service Status shows that it’s Stopped. Next, make sure Automatic is selected in the Startup Type drop-down menu rather than Manual or Disabled, and click OK.

Problem: How can I tell if my network card is working properly, or was installed correctly?
Solution: The easiest way is to use the PING (Packet Internet Groper) utility. Click Start, All Programs, Accessories, and Command Prompt. Then in the Command Prompt window that appears, type ping 127.0.0.1 and press ENTER. The numbers 127.0.0.1 constitute the standard IP address for producing a loopback network connection (though you can substitute ping localhost, as well). It should produce a listing of several lines as replies, along with a few concluding lines of statistics. If you receive a message that transmission failed or an error occurred, you probably have network card problems.

Problem: I’ve tried using PING, but nothing happens at all.
Solution: Sounds like you don’t have your TCP/IP (Transmission Control Protocol/Internet Protocol) installed. These protocols facilitate network and Internet communication, so you’ll need to install them. Click Start and Control Panel, then double-click Network Connections. Right-click the connection to your network and click Properties, then check the list of items in the This Connection Uses The Following Items field for an Internet Protocol (TCP/IP) entry. If it’s not there, click the Install button below, then double-click Protocol. Now find TCP/IP (may appear as Microsoft TCP/IP version 6) in the Network Protocol field of the Select Network Protocol dialog, click to select it, and click OK. If after installing TCP/IP you’re still not getting a response from PING, check your physical connections (make sure your network cable plugs are properly seated in their ports) and then check to see if you have a firewall running that isn’t allowing your system to access the Web. Many firewalls can be configured to refuse access without inquiring of the user whether they desire it. If that’s the case, scan the program’s interface or check its Help files for the menus and commands you can use to configure your firewall to allow outbound access. (These vary from program to program.)
Problem: I can PING a computer by using its IP address. But if I use its name, I get the following message: “Ping request could not find host [NAME]. Please check the name and try again.”
Solution: This is probably a case of not having enabled NetBIOS Over TCP/IP. As a result, your client only makes sense of IP addresses, and doesn’t know what to make of names given to computers. To fix this, click Start and Control Panel, then double-click Network Connections. Right-click your local area network connection listing and click Properties in the pop-up menu, then double-click the Internet Protocol (TCP/IP) entry in the list of items installed for your connection on the General tab. Click the Advanced button in the resulting dialog’s General tab, click the WINS tab in the next dialog, and if the Disable NetBIOS Over TCP/IP radio button is selected near the bottom of the tab, select instead the Enable NetBIOS Over TCP/IP option. Click the OK button on each of the three dialog boxes to close them. Problem: I can PING computer B from computer A on my LAN, but not the other way around. Solution: The most usual cause of this is a firewall that’s incorrectly configured. Check computer A’s firewall and see if it’s set to allow access to computer B.

Problem: I can use my network to directly browse Web pages, but when I run a program that goes out to the Web, instead, such as Windows Media Player, Norton Internet Security’s LiveUpdate, and so on, Windows prompts me to create an Internet connection.
Solution: This can occur if you use WinXP’s New Connection Wizard to create a broadband connection. The problem is that the Wizard doesn’t enable proxy automatic detection for broadband connections requiring authentication. To solve this, launch Internet Explorer, click the Tools menu and Internet Options, and click the Connections tab in the Internet Options dialog box. Click your broadband connection’s listing in the Dial-Up And Virtual Private Network Settings field, then click the Settings button to the right and select the Automatically Detect Settings checkbox under Automatic Configuration. Click OK to close both dialogs, and you should be in business.

Problem: I connect to a networked PC using my WinXP Remote Desktop Connection, then try to copy and paste data from one system to another. Either it doesn’t work or I get a message stating, “Cannot copy file: Cannot read from the source file or disk.”
Solution: This can occur if drive redirection isn’t enabled. Click Start, All Programs, Accessories, Communications, and Remote Desktop Connection. Click the Options button at the bottom of the dialog that appears, then click the Local Resources tab. Click to select the Disk Drives checkbox in the Local Devices portion of the tab, then click Connect.