causes of wifi interference

This a document discussing the causes of WiFi interference. WiFi was first released for consumers back in 1997. Since then it has played an integral role in keeping us connected to the internet at home, at work, and even in public, to the point where most of us take its existence for granted.

With every new technology comes problems and WiFi is certainly no exception, with WiFi problems being one of the most common complaints surrounding modern day connectivity. In this document we aim to look at, and offer solutions for the causes of WiFi interference which may be giving you connection issues. If you don’t find what you are looking for or your problem persists, maybe the issues you are seeing are not WiFi related and you should consider the idea that your connection problem is more fundamental – check out our general connectivity troubleshooting guide here:


Detecting a WiFi Interference Issue

If you are experiencing any of the following symptoms, it is a good idea to consider WiFi interference being the cause.

– Low signal strength even when close to a WiFi broadcast device

– A much slower connection to the internet when using connected over WiFi

– Slow file transfers between computers over WiFi

– Inability to pair WiFi or Bluetooth devices even when you are close to the receiver

– Intermittently dropping your WiFi connection


Causes of WiFi Interference

Problems associated with WiFi interference can be broken down into some main keys areas:

Physical Barriers

Regularly you will find that there is a certain spot within a building or area where you cannot seem to reach any reliable WiFi signal, no matter where you place your device. Physical barriers, such as the materials that a building is constructed with, is one of the most likely reasons for a WiFi signal being unable to reach your device. Here is a list of common building materials and the level of likely interference they are causing you:

The best way to combat a physical barrier interfering with your signal is obviously to move the router or wireless access point to a better location so the signal does not have to go through the barrier. You could also try broadcasting the signal using the 5GHz frequency, which if available will be an option with the device’s settings, but this tends to only be available on higher end equipment.

Finally, a physical barrier to a WiFi signal that most people never consider is…themselves! More specifically, your hand when holding a mobile device. Trying changing your grip for a better signal.


Frequency Interference

Frequency interference is when another signal crosses paths with your signal on a similar bandwidth and corrupts or overpowers it. Unfortunately the list of devices that has been known to cause this form of bandwidth interference is almost never ending, but here we provide a list of the common ones:

Wireless Devices – Technically speaking, any other devices that transmits or receives a wireless signal is capable of causing an interference to signal, so look to things like wireless speakers, baby monitors, walkie talkies, garage door openers.

Microwaves – Most microwaves operate on the 2.4GHz spectrum, which is the same as a lot of wireless devices, especially older or less expensive models, so massive network interference will often be experienced while a microwave is in operation.

Cordless WiFi Phones – Cordless phones also commonly operate on the 2.4GHz spectrum, so while you are talking on the phone or the phone is ringing, you will most likely see signal interference. This does not include standard DECT cordless phones, only the WiFi variety.

Satellite Dishes – If a satellite has been wired up incorrectly or the wiring is old and deteriorating, it is common for them to leak signal interference into the vicinity.

Neighbouring WiFi Network – Powerful WiFi networks, especially those seen in large corporate environments, in a close proximity to your own can affect your signal and performance, and vice versa. Installing WLAN controllers with rogue detection functionality can help detect this.

Hearing Aids – If a person with a hearing aid is in very close proximity to a wireless broadcasting device, signal disruption can be experienced.

Refrigerators – the motors on the inside of a fridge can cause disturbance with WiFi signals, as well as the fact that they are packed with ice, which can act as a barrier. Keeping WiFi broadcasting devices away from fridges is always a good idea.

External Monitors & Displays – Certain displays can emit harmonic interference, especially within the 2.4 GHz band between channels 11 and 14.

Christmas Tree Lights / Fish Tanks – both of these oscillate on the same frequency as WiFi signal and are known to be common causes of interference, not just to WiFi signal but internet connectivity in general. Avoid having internet based equipment near either of these.

Poorly Shielded Cabling – External hard drives or other devices you are connected to with poorly shielded cabling can interfere with a wireless signal and you can of course test this by temporarily removing the device to see if the signal improves. Try replacing the cable(s) that connect into the troublesome device.

In most instances, altering the broadcast channel on your WiFi device will solve a frequency interference issue. Typically a channel can be set between 1-13, try a few different ones to see which works best. Typically the best ones to use in the UK are channels 1, 7 or 13. Run a WiFi scanning tool in your vicinity (WiFi Analyzer is a good free one, available for mobile devices), check out which channel of those three is most commonly used in your area and pick one of the others. Higher end routers will allow you to broadcast on the 5GHz frequency which helps eradicate a lot of frequency issues and is the most effective solution at present.


Capacity & Coverage

A problem that often occurs, especially in corporate environments, is that there simply aren’t enough wireless broadcast devices available for users to connect to, causing overload issues in capacity. A wireless device is only capable of serving a finite amount of bandwidth, regardless of how fast the internet connection into the building is, and that amount is divided amongst the number of people connecting to it. So if for example you have an office with 50 people all connecting to the same access point, the amount of available bandwidth from that access point is divided by 50. Ensure that you don’t have one device or access point serving a high density of people in a certain area.

Coverage also plays a very important part here, so consider the distance that people are having to connect across. Signal is always stronger and more reliable the closer you are to a device, so don’t leave users a long distance away from a device they are trying to connect to. Also consider the manner in which your wireless devices are installed to provide that coverage. Wireless broadcast devices are designed to shoot their signal in a specific direction and the problem is that you can’t the radio signal to see which direction it is going. If you have access points that are lodged in the ceiling tiles or buried on a shelf in the back of a room, this is not the way they were intended to be used. Check the manufacturers guide that came with your device and the aerials to determine the intended coverage pattern and ensure they are installed correctly.


Conclusions & Resolutions

There has been large strides in recent years that has closed the gap a fair bit, but as a rule WiFi performance will always be inferior to wired performance.

To increase your chances of having a more reliable WiFi service, look primarily at the kit providing those services. Consider upgrading your kit to a device that is capable of using the 802.11ac frequency and has dual band functionality i.e. that broadcasts on both the 2.5Ghz and 5GHz spectrum. For current devices you have, never overlook the importance of a firmware upgrade. Manufacturers are constantly finding ways of enhancing the capability and performance of their devices by developing new software that runs them, so check regularly on their website for your model number and the latest firmware releases. These updates will nearly always be completely free of charge.

Metal and concrete are most certainly the highest level of obstruction risk so ensure that whatever devices you have that are broadcasting your WiFi signal are placed strategically to avoid the most amount of metal and concrete in your building.

Always carefully consider the design of your WiFi network so that capability and coverage are sufficiently catered for. If you are in doubt, speak to us about having a WiFi survey or audit, more details of which are available here:

activereach specialises in helping companies by designing and implementing digital ready networks. Give us a call on 0845 625 9025 or contact us to find out more.