How to Detect WiFi Interference on a Mac

If you’re like me, you probably have a bunch of other wireless networks that show up on your Mac when you try to connect that are not yours, but your neighbors. If you know anything about WiFi networks, you know that their are two frequencies that are currently used for all WiFi networks: 2.4Ghz and 5Ghz. The most common is 2.4Ghz and it’s also the frequency with the most congestion since all 802.11 a/b/g devices run on that frequency.

wireless networks

The 802.11 n specification will run on the 5Ghz frequency and you can usually free yourself from network interference if you run your wireless router on that frequency since it’s not as common. Most routers installed by the major ISPs like AT&T, Comast, Verizon, etc are still putting in b/g routers. If you like in an apartment, it’s a real disaster because the apartment complex usually has their own routers plus you have each person installing their own personal router, which means there are tons of routers running on one frequency.

This is normally not a problem until you have two routers running on the same frequency and same channel. On a 2.4 Ghz network, the channels range from 1 to 13, but in North America only channels 1 thru 11 are allowed. That means if there are 10 wireless routers close to you, someone is bound to be using the same channel. That’s where the interference comes in. The closer the routers that are running on the same channel, the worse the signal degradation.

That’s why if you have a neighbor with a router on the same channel, you will suddenly start seeing your connection drop even if it was working fine before. And if their channels changes, all of a sudden everything might be working fine again.

On your Mac, you can download an app from the Mac App Store that will show you all detectable wireless networks in your area and give you detailed information about each, including what channels each router is operating on. This proves to be super useful and has helped me solve a lot of my WiFi problems.

The app that I recommend after trying out a few is WiFi Explorer. You can check it out here:

http://itunes.apple.com/us/app/wifi-explorer/id494803304?mt=12

It’s not free (about $4), but it’s totally worth the price. Once you install it and run it, here is what you see:

wifi explorer

Wow that’s a lot of WiFi networks and our house doesn’t even have a neighbor yet on one side! So once they come, we’ll probably have two more wireless networks. Now the important part is the channel # on the right hand side. My networks at home are Aseem Home, Downstairs, and Downstairs-5G. As you can see, I made sure all of them have different channels than the rest of the networks that are being detected.

What’s really fun about a program like this is that you can change the channel to a conflicting one that is close by and see how your signal degrades in real time using the app. It continually refreshes every few seconds and gives you nice graphs that show signal strength over time:

wireless interference

They also have some other graphs so you can quickly see the signal strengths of all wireless networks:

signal strenghs

Other two cool graphs will show you all the networks on the 2.4Ghz and the 5Ghz so you can clearly see any overlapping networks and channels.

network channels

As you can see, the Downstairs network has fewer networks that are using the same channels or overlapping channels. With this tool, you can quickly analyze the entire area and configure your routers so that they are running optimally on a channel not being used by someone else.

Of course, this type of tool does not detect other types of devices that may be using the same frequency like your home phone, but it’s still pretty useful. If you have any questions, feel free to post a comment. Enjoy!

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