Conducting Root Cause Analysis of Common Wi-Fi Issues

Uncovering the true problem behind a connectivity issue can be complicated without the right visibility. Here are some common issues and what the root cause may be.

Key takeaways:

• Identifying 4 of the biggest causes of Wi-Fi issues:
  1. Congestion
  2. Propagation
  3. Interference
  4. Devices
• How Wireless Network Monitoring helps make finding problems easy

Determining the cause of a Wi-Fi issue can be one of the biggest challenges for IT personnel, as many connectivity and performance problems have overlapping symptoms. But the good news is that there are some common root causes of many routine Wi-Fi difficulties.

A client may be experiencing the inability to connect at all, very slow loading times, or service drops. To address these challenges and keep end-users happy, experts must conduct a root cause analysis efficiently so that the fix happens quickly and is more than temporary.

This effort benefits from understanding some of the most common root causes, what they mean, and how to avoid or resolve the problems. Here are four culprits:

1. Congestion

A sudden or continuing slowdown in service is one of the most common Wi-Fi complaints, and it is often caused by congestion. The Wi-Fi spectrum is cut up into slices, known as channels. If all the channels fill up, everything slows down, just like a traffic jam. We have a limited spectrum to work with that can sometimes get congested quickly. 

You need more channels to accommodate more activity, and proper planning enables using all the channels available and employing them correctly. In the 2.4 GHz band, there are really only three usable channels: 1, 6, and 11. These channels are non-overlapping and can fill up fast. 

On the other hand, the 5 GHz band has 24 non-overlapping channels, which is why engineers often use band-steering technology to direct people to this band, so there is less congestion. Band steering involves lowering the advertising of the 2.4 GHz band and increasing that of the 5 GHz band.

The 7SIGNAL platform gives engineers visibility into which channels are open at a given time so they can transition into those channels and have much faster Wi-Fi.

Note that some networks with the right equipment in the right part of the world now have access to the 6 GHz band with 29 non-overlapping channels. This expansion provides even more opportunities to avoid congestion. 

2. Propagation

Users may not be able to connect to the Wi-Fi at all, even though they’re in a space the network is supposed to cover. This is where propagation often comes into play.

Lower frequencies (like 2.4 GHz) can propagate signals much farther than higher frequencies (5 GHz or 6 GHz) since the electromagnetic pulse can travel farther and penetrate surfaces more easily. The higher frequency signals can’t travel, or “propagate,” as far and have a harder time getting through surfaces. 

A dual-band access point has both 2.4 and 5 GHz and can flip back and forth between them. If users are close enough for 5 GHz propagation, they can take advantage of that less-crowded highway. But devices that are farther away from the access point may not be able to join the higher-frequency network.

The device makes the final decision, and the adapter and driver work together to see what’s going on in the environment and determine which network to join. But sometimes, the device makes a poor choice. So, you want to be able to connect to the less congested band manually. For example, if you're in a building with many people or businesses, you might rarely want to be on 2.4.

Thus, an organization may need to add additional access points or create mesh networks throughout the space. These devices communicate with one another and allow users to seamlessly roam from one station to the next, ensuring a continuous, quality signal.

Note that certain surfaces are barriers to propagation; radio waves have trouble getting through them. The two biggest concerns for Wi-Fi are metal and concrete. The signal reflects off of metal surfaces, and concrete absorbs radio waves. This can be a good thing when it insulates you from “noisy” radiofrequency neighbors, but it can also get in the way of Wi-Fi spreading through rooms where service is needed.

3. Interference

The number-one interferer of Wi-Fi is other Wi-Fi networks, though many sources of radio frequencies can impair performance. These stray signals interfere with the intended signal so that a client device cannot “hear” the specified router or access point, and the AP can’t hear the device. Subsequent connection retries caused by interference lower data rates and slow down the user’s Wi-Fi experience.

One solution is finding a quieter place, which usually involves switching from the 2.4 GHz to the 5 GHz band. As mentioned, channels on 2.4 GHz can get noisy—but so can 5 GHz. That’s why 7SIGNAL’s tools show you what channels look like in real-time. Fewer neighbors and no overlapping channels mean less interference and congestion.

4. Device issues and roaming

You can still be on a channel with little traffic or interference and experience slowdowns. If this is the case, the culprit could be the device that’s trying to connect. 

For example, an individual may be using a laptop that’s not even capable of getting on a 5 GHz network, limiting the solutions beyond purchasing new equipment. Look to the wireless adapter information on the device. As long as it has the letter "A," i.e., it says “Wireless AC,” it can connect to the 5 GHz band. 

Otherwise, the root cause may be roaming issues, which signifies a WLAN adapter and driver problem. Sometimes, a client device is “sticky,” meaning that it refuses to roam to a nearby AP where it could get a better signal. Fortunately, the Mobile Eye from 7SIGNAL helps IT managers detect when this is happening. All you have to do to resolve the issue is disconnect the device from the network and reconnect, and the adapter will choose the closer AP. 

Figuring out the cause of 4 common issues and many more

Conducting root cause analysis of a Wi-Fi issue means walking through the potential causes of these common problems:

• Roaming: If you find that you have a roaming issue, it may mean your device drivers need to be updated. 

• Coverage: You might just be too far away from the router or access point. Get closer or move the AP to the middle of the desired space for better coverage.

• Congestion: Try to find the channel that’s less congested and is non-overlapping.

• Interference: If there’s a lot of noise and interfering networks, you need to switch channels and get somewhere quieter. 

Those aren’t the only problems and remedies with WLANs and devices, and 7SIGNAL helps you uncover and address all of these issues and many more. Our platform provides detailed visibility into what’s happening and causing the problem. And our built-in troubleshooting guide helps you identify the resolution. 

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