Small Business Networks: Troubleshoot a Downed Internet Connection
Whether you work from home on a single PC or you manage small business networks, chances are good that, at one time or another, you've opened a Web browser and instead of being greeted by Google you got "Page Not Found." Fortunately, troubleshooting a downed Internet connection isn't as intimidating or as complicated as it seems.
Whether it's one PC or many, the rules and techniques for troubleshooting Internet problems are basically the same. All it takes is some patience and a bit of common sense. I'll highlight the basic steps to take the next time your small business network fails to connect to the Internet.
Step 1: Restart Your PC and Router
It might sound like the obvious starting point, but you'd be surprised how many people don't try this before sounding the alarm. Yet a simple reboot can actually resolve many of the everyday issues you run into, including a flaky network connection.
Shut down all of the relevant hardware, which includes the PC, the router and the ISP's modem. In some cases the router and modem are integrated into a single unit. And obviously if none of the other PCs in your environment are having this issue you don't need to reset the modem and router, but always try rebooting the computer.
Once you shut down everything, wait at least 5 minutes and restart the devices in this order:
- The ISP's modem. Then wait 3 - 5 minutes.
- Next restart the router. Again, wait 3 - 5 minutes.
- Finally restart your PC, and try to get online.
In most cases, that will do the trick. If not, then you need to search for other possibilities.
Step 2: Isolate the Network Problem
Isolating the problem is not just saying, "I can't get onto the Internet." That's just a symptom or a result of the problem. To resolve it, we need to discover the cause of the problem. How do we do that? Like a good detective, we investigate and ask questions.
For instance, is your machine the only one having the problem, or is it all of the PCs on the network? If it's just your machine then it's probably not the Internet connection itself, but a problem exclusive to your system. On the other hand, if the problem is affecting multiple PCs, then you need to look for other factors, such as how those machines are connected to the Internet. Are they using a wired or wireless connection?
If they all use a wireless connection, then it could be a problem with the access point. If instead they all use a wired connection, then it might be a problem with the switch. If both the wired and wireless PCs are affected, then it could be a problem with the router or the ISP.
In some cases the problem might occur using Internet Explorer, but not when using Google Chrome. This could indicate a problem with the Internet Explorer application itself. In other cases you might not be able to browse the Web, but you can still get email. That would indicate that your Internet connection is fine, but something is blocking HTTP data traveling over port 80, but not email traveling over port 25. This might lead me to suspect a firewall issue or possible virus or malware infection. Once you identify the potential problem area, you can begin troubleshooting.
Step 3: Follow the Network Path
When you have a problem establishing an Internet connection, one of the ways to resolve it is to determine where the communication breakdown is occurring. You can test this by using the Ping command to trace the data path out of your network and to the Internet. To do this, you'll need to know your PC and router/gateway IP addresses.
You find these by running IPCONFIG at the Command Prompt. Typically the IP address will start with a 192, but 172 and 10 would also be valid. If you find your PC has an IP address beginning with 169, then it is invalid and would explain why you can't get online. This could indicate either a problem with TCP/IP or your router. You can learn more by reading this article about the origin of the 169 address.
If you have a valid IP address, try using the Ping command to verify that your computer can communicate with other systems. Go to the Command Prompt and type ping x.x.x.x where x is the IP address of the device you're trying to reach. You first want to try pinging devices on your network, like other PCs or printers. If you can reach those, try Pinging the gateway.
If you can reach the gateway, try pinging and external site like Google.com or Yahoo.com (example: ping google.com). If that fails, try pinging a couple of public DNS servers such as 18.104.22.168 or 22.214.171.124. If you can successfully ping the public DNS, but not the external site, you might be dealing with a DNS issue. Should that be the case, you could try replacing your current DNS with another one. Here's a list of public DNS servers you could try. If you can't reach either, it could be a problem with your router or ISP.