Picking the best WiFi Channel - what's more important? #of devices or strength of each?

[alexb75]

I Iive in a condo with literally DOZENS of different WiFi signals from all over messing up my connection specially under 2.4GHz.

I have downloaded all sorts of tools and can review all signals and what channels other routers are using, and pretty much all 13 channels are used. Now, channel 1, 6, 11 are absolutely booked, 25, 32, and 24 devices respectively. The lowest used channels are channel 2, 5, 7, 8, 10.

I used all channels and did "speed test" as well as file transfer from my router, and it looks like channel 8 is fastest, but not sure how reliable those tests maybe.

Now, my question is... should I use the channel that's least used, OR, should I be using one that has the lowest signal strength. I was once told it doesn't matter which exact channel # is used, as it may operate in the 20-40 MHz range.

PS. My 5GHz signal is pretty good and I try to use that for most devices but many of my equipment only have 2.4GHz so have no choice.

 

[ex_bubblehead]

Channels 1, 6 & 11 are the only channels that do not overlap one another. All other channels overlap at least 4 other channels ( https://en.wikipedia.org/wiki/List_of_WLAN_channels ), adding to the interference problems. Your best bet is to use the least crowded of channels 1, 6 or 11.

 

[Solandri]

The 2.4 GHz channels overlap. When you pick channel 1, you're actually broadcasting on frequencies used by channels 1-5. When you pick channel 3, it's using frequencies for channels 3-7, etc. 1, 6, and 11 are frequently used because they're independent (channel 1 won't stomp on 6 and 11, etc). So I expect your device count per channel is not really accurate.

There's no right answer to your question. The proper way would be to monitor signal strength on those frequencies for a few days, and pick the one with the lowest average signal strength during that time.

5 GHz is really a much better choice - it has a lot more channels and they're all independent. Are your 2.4 GHz-only devices in the same general area? If you can find a 5 GHz wifi router which supports client bridge mode (any router which supports DD-WRT / Tomato / OpenWRT can do it), you can set that up and any device you plug into its LAN ports will be connected to your network over 5 GHz.

 

[alexb75]

Thanks. What I don't understand is that why would they then stick to one channel only when I scan them? I haven't seen any of other wifi routers or mine to switch from 6 to 7 or back. Now for testing various signals for a time is there a tool that I can use to monitor this over w long period? I used WifiInfo app and it works great but I have no idea how to use it to pick the best channel as all are taken?

Speaking of testing. I literally tested every channel, using SpeedTest.net and to test speed transfer of 1GB file from my router. It was 100% slowest on channels 1, 6 and 11. How do you explain that? For instance while it was getting 7-8MB/s file transfer speed on channels 2,8, I couldn't get over 4MB/S on 1, 6 or 11. That meant one one it took 6 mins, on another 3.5 min.

Regarding where the devices are located. Basically they're all over the condo. The 2.4 devices are Nest, Sonos, my Panasonic Smart TV and an older laptop. All else I can do in 5GHz.

Interestingly in the farthest bedroom from router, the 2.4GHz has the strongest signal vs. 5GHz while much more interference.

 

[Solandri]

Thanks. What I don't understand is that why would they then stick to one channel only when I scan them? I haven't seen any of other wifi routers or mine to switch from 6 to 7 or back. Now for testing various signals for a time is there a tool that I can use to monitor this over w long period? I used WifiInfo app and it works great but I have no idea how to use it to pick the best channel as all are taken?

For routers that dynamically change channels, they only do so if they detect excessive interference. Bear in mind that the signals you are picking up in your location may not reflect the signals the router is picking up in its location. So while channel 6 may be crowded where you are, it might not be crowded where the router is, or vice versa.

Sorry, I don't know of an app which will monitor wifi traffic levels for an extended period of time. I was just saying that's what you'd need in a crowded environment like yours. In a less crowded environment, you can usually find a clear channel, or one channel which is least likely to have strong transmissions throughout the day.

Speaking of testing. I literally tested every channel, using SpeedTest.net and to test speed transfer of 1GB file from my router. It was 100% slowest on channels 1, 6 and 11. How do you explain that? For instance while it was getting 7-8MB/s file transfer speed on channels 2,8, I couldn't get over 4MB/S on 1, 6 or 11. That meant one one it took 6 mins, on another 3.5 min.

1 (1-5), 6 (6-10), and 11 (11-15) are probably the busiest. if someone else is transmitting on 6 at the same time you are, your signals will interfere and your throughput will drop.

If you instead pick channel 8 (8-13), then you're overlapping two of the common channels. So if you're transmitting at the same time someone else is transmitting on 6, the 8-10 portion of your signal degrades. But if channel 11 happens to be clear at that moment, then the 11-13 portion of your signal will get through. Whether or not this happens though is pure luck (depends who else happens to be transmitting at that moment).

Regarding where the devices are located. Basically they're all over the condo. The 2.4 devices are Nest, Sonos, my Panasonic Smart TV and an older laptop. All else I can do in 5GHz.

Yeah, not much you can do then. If the Panasonic TV can take an ethernet connection, you may want to figure out a way to do that instead.

Interestingly in the farthest bedroom from router, the 2.4GHz has the strongest signal vs. 5GHz while much more interference.

Remember, you actually need to measure signal strength in two locations. Measurements of the router at your device location will reflect how well the device can see transmissions from the router. Measurements of the device at your router will reflect how well the router can see transmissions from the device.

In one case, measurements I took at the router showed channel 6 was completely clear (and was why the router's auto channel selection picked 6). But when I went to the device location, it actually turned out the neighbor's router was also on channel 6, and was closer to the device than my router. It was just far enough from my router and my router couldn't see it.

 

[DeauteratedDog]

While 1, 6, and 11 are the non-overlaping channels in the US (in Europe, lots of networks are set on 1, 5, 9, and 13 to make use of the extra channels available), you already have all channels in use so that pretty much goes out the window.

Since you have actually tested all the channels, go with the one that you have the best performance on (8). It's not neighbor-friendly but sometimes you have to look out for yourself. You will need to occasionally re-test all the channels as your neighbors move to different channels.

 

[alexb75]

Thank you all, I guess I just have to test all channels and pick what's best in the location I want to use the 2.4GHz, the most critical is SmartTV and I tested transfer speeds right under the TV to be as close to where I need the fastest speed.

Interestingly, I had to get on a 6am call today so did a snapshot of the Wifi signals, and it is significantly LESS crowded at 6am... which is quite strange as I'd have imagined that routers would just be running 24/7.

 

[DeauteratedDog]

Interestingly, I had to get on a 6am call today so did a snapshot of the Wifi signals, and it is significantly LESS crowded at 6am... which is quite strange as I'd have imagined that routers would just be running 24/7.

I would expect most routers to be running 24/7 too. But probably no (or at least fewer) cell phone hotspots, or Mi-FI/Jetpack type hotspots, or cars on the road outside with built-in hotspots...

 

[Solandri]

Interestingly, I had to get on a 6am call today so did a snapshot of the Wifi signals, and it is significantly LESS crowded at 6am... which is quite strange as I'd have imagined that routers would just be running 24/7.

Routers will decrease their transmission power when they're not being used (only need to occasionally broadcast their SSID). So routers which were in use and broadcasting "loudly" enough to be detectable by you during the day, are now no longer detectable at 6 am or are being drowned out by other routers. Think of it as all the tenants in the other apartment units screaming at 5pm so you can hear all of them. But at 6am only a few are screaming, the rest are whispering and you can't hear them because the screams drown them out.

That's why I said a proper evaluation would figure out which channel sees the most traffic throughout the day (or more precisely, during the times you tend to use wifi the most).

 

[alexb75]

Interestingly, I had to get on a 6am call today so did a snapshot of the Wifi signals, and it is significantly LESS crowded at 6am... which is quite strange as I'd have imagined that routers would just be running 24/7.

Routers will decrease their transmission power when they're not being used (only need to occasionally broadcast their SSID). So routers which were in use and broadcasting "loudly" enough to be detectable by you during the day, are now no longer detectable at 6 am or are being drowned out by other routers. Think of it as all the tenants in the other apartment units screaming at 5pm so you can hear all of them. But at 6am only a few are screaming, the rest are whispering and you can't hear them because the screams drown them out.

That's why I said a proper evaluation would figure out which channel sees the most traffic throughout the day (or more precisely, during the times you tend to use wifi the most).

Thanks, good feedback, wasn't aware of how routers dynamically change their transmission power.

So, to summarize, I just need to test different channels in the locations that are needed at the right time to figure out what's best. Now, what tests are most accurate? I've been using "Speedtest.net" AND file transfer speed from router as my measurement methods, are those good tools for evaluation?

Lastly, while the channels 1, 6, 11 won't cross other channels, the fact that they're the busiest makes them less ideal and using Channels 2, or 8 that cross other channels but are used least might be better, IF my tests proved that to be case, right?

 

[DeauteratedDog]

So, to summarize, I just need to test different channels in the locations that are needed at the right time to figure out what's best. Now, what tests are most accurate? I've been using "Speedtest.net" AND file transfer speed from router as my measurement methods, are those good tools for evaluation?

Lastly, while the channels 1, 6, 11 won't cross other channels, the fact that they're the busiest makes them less ideal and using Channels 2, or 8 that cross other channels but are used least might be better, IF my tests proved that to be case, right?

My first choice for a test method is iperf - if you have a wired computer connected to your router. Speedtest is always a little bit variable just because of changing conditions on your local ISP's network and the Internet in general.

To your second point, when APs/Routers are on the same channel, they will cooperate on channel access using a scheme called CSMA/CA, when they are on different channels the other access point(s) are just background noise, reducing the signal-to-noise ratio on the channel. In your case, according to your tests, you are better off with more noise and fewer devices on the channel. In an enterprise environment, where you are managing hundreds of APs as a system, you would always choose 1,6, and 11, because that maximizes total system throughput across all the APs. That isn't your situation.

Hope this helps.