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Choosing a US 2.4 GHz Wifi Channel

Theoretically, you should only use the primary nonoverlapping channels 1, 6, and 11. Routers on the same channel share it cooperatively. But it's claimed that routers with less than four blank channels between them may block each other.

Practically, this is nonsense. You don't control the channels your neighbors are using. And every channel 1 through 11 is highly likely to be in use by multiple neighbors. So what can you do? Separation of at least 15 feet between routers on adjacent channels is said to help considerably. In a multiple occupancy building you are better off putting the router in the middle of an outside or hallway wall than on a common wall. Speculatively, at least one blank channel between nearby routers may also help.

You probably should avoid a channel immediately adjacent to any close strong-signal neighbors. That would suggest avoiding 2, 5, 7, and 10 because the primary channels will surely be used by close neighbors. That leaves 1, 3, 4, 6, 8, 9, and 11 as candidates.

You probably should also avoid channels immediately adjacent to any strong-signal channel used by immediate neighbors. Among the survivors, you might try the ones with the fewest cochannel routers.

Example. Suppose one strong-signal neighbor is on channel 2 and one on channel 8. That would counsel for also avoiding channels 1, 3, and 9, reducing the choices to 4, 6, 8, and 11. But 6 is the most heavily used primary channel, and 11 is probably also well used. Now we're down to 4 and 8. Channel 8 has only that one strong-signal neighbor, and we could certainly share that channel efficiently -- but no one is using channel 4.

That doesn't mean that channel 4 is necessarily the better choice. Remember cooperative channel sharing. In this case, testing confirmed that channel 8 gave far better wifi speed than channel 4. This is probably a product of interference such as scoundrels using 40 MHz bandwidth in the 2.4 GHz band. In this specific case, channel 8 was also much faster than any primary channel.

The experts pushing the mantra to restrict yourself to channels 1, 6, and 11 don't live in the real world. They live in the best of all possible worlds where nobody would dream of speeding, running a red light, or going without an N95 mask. But in the real world, folks aren't wearing their masks, they do run red lights, and like tachyons they never slow down to the speed limit. And yes, they do use the other channels. They're all in use. They have been for years. Get over it. And stop spouting this nonsense about 1, 6, and 11 being the only usable channels. They may be the least usable channels.

You can't completely reason out the best channel. Use an app and test what channel works best for you. The results may surprise you. Do note that in some areas Internet usage, and by extension wifi usage, soars after 6 PM, during what used to be television prime time. Testing in this period may give very different results than at 1 PM.

The app I used for testing is WiFi Analyzer Pro developed by Zoltan Pallagi, androidutils.io/wifianalyzer. To get a reasonable throughput test you will probably want to upgrade from the free to the pro version, so you can test wifi speed for at least 60 seconds. I have no financial or personal connection with this product; it just proved to be so simple and clear that even I could use it.

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