Connection difficulties arise from any number of issues, including both hardware and software; even poor positioning of an access point or its antenna can be enough to significantly degrade a signal.
This tutorial part 1, presents these issues in a condensed FAQ (Frequently Asked Questions) format, hopefully easier to read and will help you more quickly find the information you need to solve your problem.
My wireless doesn’t work. How do I find the problem?
The goal of any troubleshooting exercise is to isolate the problem so you know what you need to correct. Therefore, you need to start at either end of the connection and work toward the other end checking that hardware and software are functioning correctly.
Most people tend to start at their mobile device end because the feeling is that an established server service is likely to be more reliable than a transient laptop network node. But in truth problems show up all along the connection route.
Most of the time you don’t need to go component-to-component to diagnose a connection problem. If you have some idea what the problem might be, start with that factor and look at the components in hardware or software that impact that aspect of your wireless connection.
For example, if your laptop gets a wireless connection, but that connection is very weak or transient and changes as you move locations, then you wouldn’t start by checking the Ethernet cable between the access point and its hub.
You might want to start by looking at the antennas and signal strength of your wireless components. In real estate, the motto is “location, location, location,” but in troubleshooting, it’s isolation, isolation, isolation. So let’s look at general areas of concern before moving on to specific problems.
These are common areas of difficulty:
- Wireless access point or router’s connection to the network.
- Access point or router’s condition, both hardware and software.
- Physical positioning of devices and quality of signal.
- Network interface card of client and settings.
- Security mismatch or issue.
- Client software or hardware problem.
My laptop can’t connect to an access point, although other wireless clients in my office can. What should I do?
First make sure that it’s not your location that’s the problem. Try moving your computer to a known working location, or moving a working computer to your location. Another obvious thing to check is that you have seated the NIC in your computer correctly and that the adapter is getting power.
That is, if it is a PC Card and it has lights (almost all do), do you see any lights on? The fact that other wireless clients can connect to the WLAN means that the problem is specific to your laptop.
You need to look at several factors: your laptop’s network address, whether your NIC is functioning correctly, and whether you have the right software settings. Let’s look at how you might diagnose this with a Windows XP laptop. To check and fix your network address:
- Click Start>Run.
- Enter CMD and press the Enter key.
- Type IPCONFIG and press Enter. IPCONFIG will return information about your network settings. Your wireless network connection should show as connected and have as an address a unique IP address in the same subnet as the access point the laptop is communicating with.
That is, if your access point address is 192.168.0.1, the assigned IP address should be a valid and unique address in the range of 192.168.0.2 to 192.168.0.255.
On some networks, laptops are assigned static IP addresses. A wrong address can be corrected manually by changing the settings in the Network Connection Properties dialog box for the TCP/IP property.
- If your network address is dynamically assigned and the address is incorrect, you can force a reassignment by restarting your computer, or more conveniently by entering the IPCONFIG /RELEASE ALL command followed by the IPCONFIG /RENEW command.
When you install Windows XP networking, you also install something called the Microsoft Loopback Adapter. This is a piece of software that lets you test your network card even when that card isn’t connected to the network.
If you see an address similar to 169.254.x.x/16, then your network card isn’t getting an address from the DHCP server and you are viewing your loopback adapter address.
- Enter IPCONFIG once again and see if you can establish a valid IP address and get a connection.
Sometimes having two or more DHCP servers can be the problem. If you are getting your correct IP address reset, check that there isn’t a second rogue DHCP server.
Many access points and routers let you enable this service, so it’s easy to inadvertently establish additional DHCP servers without realizing it. If you can’t establish a valid IP address, it’s time to check your NIC and its settings.
My network address is correct, but I still can’t connect my computer to a working WLAN. What’s wrong?
The next two issues are NIC related: you need to determine whether the NIC is functioning correctly and whether the installed drivers are correct. That involves checking your device properties and perhaps swapping in a second NIC if possible.
If this is a new WLAN you are trying to connect to, make sure that the protocol(s) the WLAN offers are one(s) that you can receive. If you have an 802.11a device, don’t expect to be able to talk to an 802.11g network. To check your NIC’s device settings:
- Right-click My Computer (either on your Start menu or your desktop) and select Properties.
- Click the Computer Name tab and check that your system’s name and workgroup or domain name is correct.
- Click the Hardware tab; then click the Device Manager button.
- Scroll down to the Network adapters section and click the + sign to open that section if necessary. If there is an X or a yellow caution sign next to the name of your wireless adapters, then the problem is your NIC.
- Uninstall your NIC; then reinstall the card. Make sure that your driver software is the latest version and up to date.
- If you still can’t connect, try substituting a card that is known to work from another system and see if that solves the problem.
Not only is my network address correct, but my adapter card works properly too. What’s next?
You’ve eliminated hardware as the probable cause of the connection problem, as well as the software that is driving your hardware. The next thing to check is the software in your computer.
If you’re connecting to a known working WLAN at a location where the signal strength is also known to be strong enough, your problem may be a function of incorrect network settings. To check your network settings:
- Open the Network Connections folder from the Control Panel, and check that the network connection is actually enabled. That is, the connection label should say Enabled.
If there is a red X through the wire of the icon for the Connection, the connection is Enabled but unavailable. If you need to enable the connection, right-click the connection icon and select Enable. If that’s not your problem, soldier on.
- Right-click the wireless LAN connection and select the Properties command; then click the Wireless Networks tab. You can get to a similar location by right-clicking the connection icon in the Status tray (if you enabled that feature in your Network Properties dialog box for the connection) on the right side of the taskbar and selecting the Properties command.
- In the list of Available networks make sure that you not only see the WLAN, but also that you have selected its name. If you don’t see the name, click the Refresh button. If you don’t see your desired network, the problem is at the sending end, and you need to go to the next sections to check your access point.
- If the network you are connecting to is a third-party WLAN, click the “Use Windows to configure my wireless network settings” setting. Otherwise, leave it unchecked.
- With your desired WLAN selected in the Available networks section, click the Configure button to open the Wireless Networks Properties dialog box for that specific connection.
Check that the following are correct: the SSID or name (it must be exactly right), and whether the Network Authentication and Data encryption settings are correct. More importantly, click the Authentication tab and check the settings there.
Getting the network name or SSID exactly correct is particularly important in instances where the wireless network isn’t broadcasting its name.
- With your desired WLAN selected in the Preferred networks section, click the Advanced button to view the types of networks you can access. For your personal WLAN you should use either “Any available network . . .” or the “Access point . . .” choices.
For an ad hoc connection, set that option. If you have the checkbox “Automatically connect to nonpreferred networks” checked, uncheck that box if you are trying to connect to a preferred network.
- Close the Properties dialog box.
Some settings in the Available Wireless Networks dialog box could also be a problem, so you should check there, too. To check the Available Wireless Network settings, do the following:
- Right-click the connection icon either in the Network Connections dialog box or in the Status tray of your taskbar and select View Available Wireless Networks.
- Your desired WLAN should be listed in the Available wireless networks list box and you should select it.
- If the Connect button isn’t enabled, perhaps your network doesn’t encrypt its traffic and thus is not secure. Click “Allow me to connect to the selected wireless network, even though it is not secure.” If that enables the Connect button, click the button and test your connection.
- If enabling the checkbox in Step 3 doesn’t fix the problem, even though you’ve clicked the enabled Connect button, then it’s time to move on to diagnosing problems with your access point.
Rare instances occur where an entire TCP/IP networking stack becomes corrupted. That is, no matter what you do there is an error in the networking software in your computer.
Windows XP is supposed to “self heal” and fix problems like that, but these issues are still possible, if unlikely. When you’ve eliminated all of the other possibilities you may want to remove your networking components and reinstall them. You can perform this operation from the Add/Remove Software Wizard in the Control Panel.