Reset Your IP Address
If your system's connection to a network is unreliable, or you're getting IP address conflict error messages, try renewing your IP address. First, click on the Start button, navigate to the Command Prompt (Start Menu, Applications, Accessories, Command Prompt), right-click it, and select Run as Administrator from the menu. Then type ipconfig /renew, and press Enter. That should do it.
Flush Your DNS Cache
Whenever you type a URL into a Web browser, your PC asks your domain name service server (DNS server) to translate that URL into an IP address, and caches that information. That cache can occasionally become outdated or corrupt, which can cause Internet connection problems. To clear your DNS cache, open the Command Prompt with Run as Administrator, type ipconfig /flushdns, and press Enter.
Reset Your Broadband Modem and Router
Your broadband modem's connection to the Internet will occasionally become unreliable, and restarting it can fix that. The same trick also occasionally works for the connection between a router and a broadband modem.To reset your broadband modem and router, disconnect their power cables and leave the modem and router off for 30 seconds. Don’t just press the power buttons--that can occasionally put modems or routers into standby mode rather than totally killing the power. Next, reconnect the modem's power cable to restore its power. Wait a few moments for the modem to renegotiate its connection to the Internet and establish a solid link; then plug in the router. Once the router has completely booted up, follow the steps outlined earlier to renew your system’s IP address. You should then be good to go.
Configure Wireless Security
The vast majority of wireless broadband routers available today ship with their wireless security features disabled. This makes it easy for novice users to set up a wireless network in their homes or offices, but it also leaves your network vulnerable to prying eyes.Although the exact procedure necessary to enable wireless security will vary from router to router, in general the steps required to access the pertinent options will be similar.
Assuming your router/gateway’s IP address is 192.168.1.1 and you’re connected to the network, open a Web browser on a system that is phsyically wired to your network and type 192.168.1.1 into the address field. You’ll then be prompted to enter the necessary credentials to access your router’s configuration menus (consult the manual for your router’s default username and password if you didn’t set them yourself. And if you didn’t set them yourself, change them right away to prevent unwanted tampering).
Open and Forward Ports
Some applications require that certain network ports be opened and forwarded to the correct PC for some of their functions to operate across the Web. Game servers are a great example: If the correct network ports aren’t opened and requests on those ports aren’t forwarded to the correct PC, inbound traffic on them will never make it through your firewall.As always, though the exact process necessary to forward ports will vary, the steps required to access the pertinent options within any router will be similar. Check out our guide to port forwarding for more information.
You’ll need to create a ruleset that tells your router which protocol to use (UDP, TCP, or both), defines the port range you want to forward, and specify to which IP address the traffic on those ports should be forwarded to. For example, if the machine running the application you are troubleshooting has an IP address of 192.168.1.115, put that string into the IP address field. Save the settings to enable the rule, then reboot the router to finish the job.
Put a System in a DMZ
Sometimes port forwarding isn’t enough and you’ll have to give a system unfettered access to the Internet. In those cases, the machine can be placed in a network DMZ, or demilitarized zone. Putting a system in a DMZ means all of its ports will be accessible from the Internet; such a situation is very dangerous, so don’t take that step unless it is absolutely necessary.
When you're on the DMZ configuration menu, you’ll need to enable the DMZ and specify the IP address of the system you’d like to place in the DMZ. Enter the IP address, save the settings, and reboot the router; that system should now be in the DMZ.
Update Network Drivers
Like any other peripheral in a Windows PC, the network controller requires drivers to operate. Those drivers tell the operating system how to use a device and occasionally need to be updated to resolve issues or add new features and capabilities.Updating network drivers in Windows is usually done in one of three ways: through the Windows Update software, by downloading and running an executable installer, or by manually choosing a driver through Device Manager. When possible, use the first method: Updating a driver through Windows Update is easy and automatic. Unfortunately, manually installing a driver through Device Manager is a bit more complex.
If you’ve downloaded a driver for your network interface card from the manufacturer’s website and the file contains nothing but some .inf or other nonexecutable files, you’ll need to manually install it using Windows Device Manager. To do so, click on the Start button and type Device Manager in the search field. Press Enter to open the Device Mananger, find Network Adapters in the list of devices in the system, right-click on your network controller, and select Update Driver Software from the menu.
In the new window that opens, click on the Browse my computer for driver software button; then click on the Browse button and navigate to the folder where you placed the newer driver you downloaded. Click the Next button, and the driver should install automatically.
Disable or Add Exclusions to Windows Firewall
Windows 7's built-in firewall constantly asks you to allow or deny an application's access to your network. If you've mistakenly blocked an application and want to unblock it (or the other way around) you'll have to manually change some settings in the Windows Firewall control panel.
Scan Your Network for Attached Devices
With so many connected devices now on the market, there may come a time when you want to scan your entire network to see exactly what devices have obtained IP addresses and are consuming resources. Your router may be able to check the status of connected clients, or you could use a third-party application that will more comprehensively scan an entire range of IP addresses to find and obtain information on the connected devices.
Diagnose Internet Connection Issues
Finally, one problem that may be beyond your immediate network: Is your Internet connection unstable--and you can't figure out why? A couple of utilities built into Windows 7 may help. Ping and tracert (traceroute) can help you find out if your Internet issues are with your home network or with your ISP--or somewhere in between.
Tracert is another useful tool that will list the route and measure transit delays of packets across a network. To use Tracert, open a Command Prompt window and type tracert google.com. This will essentially map out the path from your PC to a Google server, listing the IP addresses of the servers and switches in between. Usually your packet's first few hops will start in your home network, then go through your ISP's network, and then eventually find their way to google.com. If the packet doesn't make it out of your network, the problem is inside your network; if it doesn't get past your ISP's network hubs, your ISP probably has a network outage or equipment failure (yes, a busted Internet connection isn't always your fault).