2.4GHz and 5GHz conflicting channels? Is this even possible?

[Jones586]

Router: Netgear Nighthawk R7000

I have been having issues with the speed of wireless signal on my router. Speeds are slow when on default settings. Default channel for 2.4GHz is auto and channel 153 for 5GHz. At the default channels the 2.4Ghz runs about 15-20Mbps down and 12Mbps up and the 5GHz will run about 35Mbps down and 12Mbps up. I called Netgear and most of their reps don't speak good enough English to help.

My hardwired speed is about 120Mbps down and 12Mbps up.

When I change channels I get various speed responses, for example I tried channel 11 on the 2.4GHz and and channel 153 on 5GHz. This responded with 8Mbps down and 12Mbps on the 2.4GHz and 117Mbps down and 12Mbps up on the 5GHz.

The best combination I have found is channel 9 for the 2.4GHz and channel 161 for the 5GHz. This responds with about 25Mbps down and 12Mbps up on the 2.4Ghz and 60Mbps down and 12Mbps up on the 5Ghz.

The speeds are very choppy as well except when I had the 5GHz connect at a good 117Mbps down.

I didn't think they could conflict with each other like this because they are totally different bandwidths but apparently something is conflicting and causing them to slow down. I have tried just about every channel combination and I don't think it has anything to do with the channels I think it's something else and I have no idea what. Hopefully this isn't too confusing and someone can help.

Thanks!

 

[Solandri]

You've got several things going on at once so it's hard to pin blame down on one specific thing.

First, don't test your wifi speeds to the Internet. Plug in a computer to your router with an Ethernet cable. Share a folder, and put a big file like a movie in the folder. Measure your speeds by copying that file to/from your laptop over wifi. Or you can try some of the programs out there for testing network (LAN) speeds.
https://www.raymond.cc/blog/network-benchmark-test-your-network-speed/

Second, get WiFi Analyzer for your Android phone. If you have an iPhone, there's probably a similar app. It'll let you see all the wifi networks in the area, what frequencies they're at, and how strong they are. The variability in your test results may simply be because a neighbor began streaming Netflix over wifi during one of your tests.
https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en

2.4 GHz channels overlap. Each "channel" actually only gives 1/5th the bandwidth of a full connection. So when you set your router to channel 1, it's actually transmitting over channels 1-5. When you set it to channel 6, it's actually transmitting over 6-10. And channel 11 transmits over 11-15. That's why most people use only channels 1, 6, and 11. If you set it to channel 9, it's using 9-13. So you're covering some of the bandwidth used by devices set to channel 6, some of the bandwidth of channel 11.

This is good in that someone saturating channel 6 with Netflix won't bring your wifi to a standstill, because you can still partially communicate over bands 11-13. It is bad in that now channel 6 and channel 11 users will interfere with your signal. Still, if there are a lot of wifi users nearby, this may be the only way to get a decent signal.

5 GHz doesn't suffer from this problem. Each channel is completely independent. However, because it's a higher frequency it attenuates faster as it passes through walls, furniture, people, and even air. So its range is not as good. Little things like which way your laptop is oriented, and the kids/dog running between your laptop and router will affect 5 GHz more than 2.4 GHz. (OTOH, 2.4 GHz is destroyed by running a microwave oven, which emits at 2.45 GHz, which is smack dab in the middle of channels 6 and 11.)

2.4 GHz ranges from 2.412 - 2.494 GHz.
5 GHz ranges from 5.170 - 5.835 GHz.

So there shouldn't even be any 2:1 resonance interference between the bands.

 

[Jones586]

You've got several things going on at once so it's hard to pin blame down on one specific thing.

First, don't test your wifi speeds to the Internet. Plug in a computer to your router with an Ethernet cable. Share a folder, and put a big file like a movie in the folder. Measure your speeds by copying that file to/from your laptop over wifi. Or you can try some of the programs out there for testing network (LAN) speeds.
https://www.raymond.cc/blog/network-benchmark-test-your-network-speed/

Second, get WiFi Analyzer for your Android phone. If you have an iPhone, there's probably a similar app. It'll let you see all the wifi networks in the area, what frequencies they're at, and how strong they are. The variability in your test results may simply be because a neighbor began streaming Netflix over wifi during one of your tests.
https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer&hl=en

2.4 GHz channels overlap. Each "channel" actually only gives 1/5th the bandwidth of a full connection. So when you set your router to channel 1, it's actually transmitting over channels 1-5. When you set it to channel 6, it's actually transmitting over 6-10. And channel 11 transmits over 11-15. That's why most people use only channels 1, 6, and 11. If you set it to channel 9, it's using 9-13. So you're covering some of the bandwidth used by devices set to channel 6, some of the bandwidth of channel 11.

This is good in that someone saturating channel 6 with Netflix won't bring your wifi to a standstill, because you can still partially communicate over bands 11-13. It is bad in that now channel 6 and channel 11 users will interfere with your signal. Still, if there are a lot of wifi users nearby, this may be the only way to get a decent signal.

5 GHz doesn't suffer from this problem. Each channel is completely independent. However, because it's a higher frequency it attenuates faster as it passes through walls, furniture, people, and even air. So its range is not as good. Little things like which way your laptop is oriented, and the kids/dog running between your laptop and router will affect 5 GHz more than 2.4 GHz. (OTOH, 2.4 GHz is destroyed by running a microwave oven, which emits at 2.45 GHz, which is smack dab in the middle of channels 6 and 11.)

2.4 GHz ranges from 2.412 - 2.494 GHz.
5 GHz ranges from 5.170 - 5.835 GHz.

So there shouldn't even be any 2:1 resonance interference between the bands.

Thanks for the response.

There is only one other wifi signal that my devices pick up nearby, it's an AT&T router. I'm doubting interference from my neighbors is the source of the problem. I downloaded that app on my phone and I don't see where to see what channel they are on, it only gives me info on the wifi signal that I am connected to.

I still don't understand how when I change the channel of just the 2.4GHz it can slow down the speed of the 5GHz channel. Like right now my iPhone is connected to the 5GHz according to it I'm running 117Mbps down with a very smooth connection, if I connect it to the 2.4GHz its about 24Mbps down and the connection is not smooth at all. Right now my 2.4Ghz is on channel 11, if I change it to 6 or 1 it makes both the 2.4GHz and the 5GHz run choppy and slow.

My laptop isn't available right now so all I have to test with is my Iphone but I have done the download tests in the past an I have always had similar results as to what any speed test site gives me. I made sure all my other devices are not turned on so they can't impact my tests and I usually test 3-4 times over a 10 min period and get similar results.