Troubleshooting Wi-Fi Issues

Introduction

Though wired connections usually serve as the backbone and default connection method for stationary computers and devices on the network, wireless connectivity is also crucial for most these days. As you may know all too well, Wi-Fi can also be a pain. The airwaves are susceptible to interference and many other issues that cables aren’t.

No connectivity at all for any devices to an AP

If no one can connect to a certain AP, before rebooting it check if the AP is powered on and check its status. If the AP is mounted where it’s visible, go to it and check its status lights and refer to the APs manual or documentation on the meaning of the lights.

Next, try to check status further by logging into it’s web GUI via the IP address or by checking the wireless controller. Take a look at the current client list of the AP to see if anyone is connected and look through any logs. Also check the status of the uplink connection to the AP, to ensure the data rate and duplex is correct for the Ethernet connection.

If problems persist after rebooting an AP, perhaps try resetting it to defaults and re-configuring the AP. If the issues keep coming back every so often, check with the AP vendor and do some online searching. Maybe there are known issues with the model, like overloading which could possibly be helped by disabling certain features or functions.

Connectivity issues for a particular device

If only one computer or device is having connectivity issues, try a good old reboot. If problems persist and the device is using a USB wireless adapter, unplug it and plug it back in to see if that helps. Furthermore, if it’s a Windows, Mac, or Linux machine, try removing the driver for the wireless adapter and re-installing it or a more up-to-date driver if available.

If the problem device is a laptop, another thing to look for is a physical Wi-Fi switch or button on the laptop itself. If the laptop has a button for the Wi-Fi, it could have been accidentally pressed, disabling the Wi-Fi altogether.

If you’re having connectivity issues with an older printer or other device, ensure it supports the security type enabled on your Wi-Fi. For instance, some older printers and devices support only the first version of W-Fi Protected Access (WPA) security with TKIP encryption and your APs might be set with only the second version: WPA2 security with AES encryption.

Intermittent connectivity or slowness

If you’re having intermittent connection issues or slowness with your Wi-Fi devices, it could very well be co-channel interference from your other APs or neighboring networks. This is especially the case if the devices having the issues are on the 2.4GHz frequency band versus the 5GHz band. You can check channel usage with a simple Windows, Mac, or mobile app. However, keep in mind that those simple apps might not accurately show the correct channel-widths. Using a professional grade Wi-Fi analyzer is best for accuracy.

When looking at the 2.4GHz channels, keep in mind that only three of the 11 channels don’t overlap with each other. Thus you should generally stick to using channels 1, 6, and 11 on your APs so each AP is on a different non-overlapping channel. Furthermore, you don’t want the coverage of APs on the same channels overlapping. Thus for networks with multiple APs, you want to stagger the channel assignments. If you have more than three APs, you can reuse the three non-overlapping channels of 1, 6, and 11, but just reuse them so there’s no interference with other APs on that same channel.

After looking at the channel usage of any neighboring networks, take some time to plan out what channels your APs should use. Usually it’s best to begin assigning channels to the APs on the outer edge of the coverage area and work your way inside. That way you can analyze neighboring networks and choose the best channels for those APs that are most affected by outside influences, then you can assign the inter APs channels.

Keep in mind that even professional grade Wi-Fi analyzers don’t by default show other RF interference. So if it continues to look like there’s interference issues and you can rule out simple channel overlapping, consider using an RF spectrum analyzer. That looks for other sources of interference, such as from cordless phones and other wireless devices affecting the 2.4 and 5GHz frequency bands. Some Wi-Fi analyzers support adding on a RF spectrum analyzer.

As a general rule of thumb when it comes to reducing Wi-Fi interference, try to use the 5GHz frequency band as much as you can. Though devices have shorter ranges, the band is much bigger, supports more channels, and is less-congested than the 2.4GHz band. If your APs don’t already support it, I suggest upgrading to dual-band APs with 802.11ac or 802.11n. Though not all computers and devices support the 5GHz band, more and more are these days. For client devices that are upgradable, you could consider updating them to support dual-band as well. You want as much devices as possible on the better band to help increase the Wi-Fi performance and reliability.

Roaming issues for moving clients

Wi-Fi networks with more than one AP are designed to allow the wireless computers and devices to roam between them when the SSID(s) of each AP match. Ideally, this roaming should be seamless to the user and not interrupt any network activity. However, many factors influence the roaming process and experience.

One of the biggest issues with roaming is clients sticking to a certain AP, particularly keeping a connection to an AP with a lower signal after moving locations to where there’s an AP with a higher signal nearby. Though the decision of which AP to connect to and when to roam is really up to the client, you can try to prevent this type of issue by disabling the slower data rates like 1, 2, 5.5, or 11 Mbps supported by the APs. That way clients are basically kicked off when the data rate goes that low, which generally means when the client is on the fringe of that APs coverage. Then the client will be more willing to connect to an AP with a higher signal.

Summary

Remember, in addition to rebooting problem APs, check it’s status, uplink connection, and logs for any clues. For problem devices, in addition to rebooting, reinstall the wireless adapter’s driver if possible and reset the wireless adapter if it’s USB. If it’s a laptop, check for a physical button or switch for the Wi-Fi. If it’s a printer or other device, ensure it supports the exact security method used by the Wi-Fi.

Remember that interference from neighboring networks and even your own APs can cause connectivity and performance issues. Do a good channel analysis to ensure there’s no (or minimal) overlapping of channels in the 2.4GHz band. And always try to utilize the 5GHz when possible.

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