Very basic network troubleshooting

In a former technical support role, my colleagues and I received numerous calls and emails from customers regarding our network-connected devices that “weren’t communicating.” In some cases, those customers had legitimate complaints: network cards occasionally needed to be rebooted, and every once in a while an Ethernet adapter would actually fail completely and need to be replaced.

It was at least as common, however—and I think I could make a strong argument that it was more common—for the connectivity problems to not be related to my employer’s hardware at all! I wouldn’t necessarily expect the average user to perform network troubleshooting, but having to almost beg IT staff with some organizations to check their own network and their own equipment got old in a hurry.

With that in mind, I thought it would be worthwhile to compile a few basic troubleshooting tips that often helped me and the customers I was supporting determine whose team really needed to look into the problem. This is not intended to be a complete list of potential problems, but if you are new to technical support, or even if you are simply an end user trying to figure out whom you need to contact, these things may get you pointed in the right direction.

#1: Is the device turned on?

This one is so obvious that I almost hate to even ask the question, but seriously: is the device turned on? Are you sure it’s turned on? If someone disconnected the power adapter, or if your electrician flipped the circuit breaker so he or she could work on an electrical issue, and the device in question is powered off, you’re not going to be able to communicate with it.

#2: Is the device connected to the network?

I could just as easily have made this #1. Again, I hate to ask the question, but if we’re talking about a hard-wired device, does it have an Ethernet cable connected to it? Is the other end of the Ethernet cable connected to anything? Are there any Ethernet cables hanging loose at the nearest network switch?

Likewise, if the device in question connects to your network via Wi-Fi, does it actually show as being connected? Can you even see the network’s SSID if you take a quick peek at your phone?

In either case, if the device is not connected to the network, either physically or via Wi-Fi, you’re not going to be able to communicate with it.

#3: Are you able to ping the device?

Assuming that you’ve already checked the first two items—and you did confirm that the device is powered on and connected to your network, right?—my next recommendation is to try pinging its IP address from another computer on your network.

If you’re using Windows, you can open a command prompt by pressing Windows + R, then entering cmd and clicking OK. In the command prompt window, type ping, replacing the IP address with your device’s IP address, and then press Enter. You’ll likely find one of the following:

  • If you get a response with time values, then something with that IP address is connected, and we can troubleshoot from there.
  • If you get a response indicating that the request timed out, there could be a problem with the device in question, or there could be an issue elsewhere on the network. Proceed to item #4. (Note that some devices are configured to not respond to ping, so the lack of a response here may not necessarily indicate a lack of network connectivity.)
  • If you get a response indicating the destination host unreachable, there is probably a network issue that your network staff will have to investigate. Proceed to item #4.
  • If you get a message stating that the TTL expired in transit, a network device is misconfigured, and your network staff will have to investigate. Proceed to item #4.

#4: What does tracert show?

Using the command prompt window that you opened previously, try entering tracert, once again replacing the IP address with your device’s IP address, and then press Enter.

Depending on your network, you may initially see IP addresses or sever names along with response times listed in milliseconds, but eventually you will probably see asterisks along with the message, “Request timed out.” Provide your network staff with the last IP address listed with response times, which is the last network device from which your computer got a response, and that may help them narrow down where the problem lies.

One exception to this is when there is a network misconfiguration. In that case, you may see the same pair or sequence of IP addresses repeated over and over again. Even if that’s the case, you’ll still need to send the information on to your IT staff for further investigation.

#5: Does a different device connected to the same Ethernet cable as the device you’re troubleshooting have network connectivity?

One other thing you can do is configure a laptop to use the same network settings (IP address, subnet mask, and default gateway) as the device that you’re troubleshooting, then disconnect the Ethernet cable from the problem device and connect the cable to your laptop. If your laptop has network connectivity, you’ve confirmed that the physical connection itself is good.

I should add that not having network connectivity at this point doesn’t necessarily mean that there’s a network-related problem. Depending on firewall and switch configurations, and whether or not your IT team is doing any sort of MAC filtering, it may be impossible to connect your laptop to the network in this way, but if it does work, then you can rule out the network being the problem.

Wrapping it up

Again, this is not an exhaustive list, but simply a few questions that I’ve commonly asked when attempting to troubleshoot problems with devices not communicating over a customer’s network.

Once you’ve worked your way through this list, if you still haven’t identified the problem, then it’s time to escalate the issue to your IT staff or the support team for the device in question. Doing these few basic checks first, however, can save you and everyone else some time.

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