This article is part of the "Why is My WiFi slow?" training series.
All too often, the culprit of slow WiFi is use of the 2.4 GHz band, which offers slower data rates and is often oversaturated with WiFi and non-WiFi devices, like microwave or baby monitors.
Most WiFi devices are designed to steer back and forth from one band to another as they move around. Since the 2.4 GHz wavelength is longer and pierces through walls and material more easily, devices will use the 2.4 GHz band as they get farther away from the router or AP. However, sometimes they get stuck on the 2.4 GHz band even when they are close enough to use the 5 GHz.
In the example above, a ChromeCast and Apple device are associated to the 2.4 GHz band. The 1st generation ChromeCast is not capable of using the 5 GHz band and therefore won’t be steering to it anytime soon. The Apple device, however, can and should steer to the 5 GHz band whenever possible.
How do you know if the 2.4 GHz band is oversaturated? Well, you can’t… unless you have a spectrum analyzer. Since RF is invisible to the naked eye, you must use a spectrum analyzer like the Wi-Spy DBx in order to see it. With a Wi-Spy DBx plugged in, inSSIDer will show you exactly how much the spectrum is being utilized and display any significant interferers. The image below shows a cordless phone wreaking havoc on channels 3-7. The interference from this cordless phone would be invisible without a Wi-Spy.
OK, how do you know if any clients are using the 2.4 GHz band? Luckily, with a MetaGeek Plus subscription and compatible wireless adapter, inSSIDer can show you this.
Plug the adapter into your computer and open inSSIDer.
Find your your wireless network’s name, or SSID, and dive into the Network Details by clicking the binoculars icon.
Keep an eye on the clients column and see how many clients are on each radio on your network. Find your 2.4 GHz radio (hint: it will be on channel 1-13) and click the binoculars icon again.
If the problematic device is listed under your 2.4 GHz radio, try turning the WiFi on that device off and on again to ensure it’s choosing the optimal band.
If your device is still stuck to the 2.4 GHz band, see if you can log in to your router configuration utility and disable the 2.4 GHz radio entirely, forcing all traffic to the 5 GHz band. Not recommended if you have really old devices like a Nintendo Wii or 1st generation ChromeCast! Not all routers will let you do this. If yours doesn’t, go to Step 7.
From your router configuration utility, give each band its own SSID name in order to segment clients and to ensure they don’t steer down to the 2.4 GHz band. For example, name your 2.4 GHz network MyWiFi and name your 5 GHz network MyWiFi5G.
Associate your problematic device to the 5 GHz network. Now it won’t connect to the 2.4 GHz network! Once your devices are using the frequency band that you want, be sure to choose non-overlapping channels.