2.4g connection unstable while 5g works perfectly

[fredtsai]

Well, I tried to look for similar situation but unfortunately I wasn't able to find one, and thus I created this new discussion.

I have the R6900 Nighthawk AC1900 setup at my living room. In fact I got this router about 4 months ago this March (2017). The setup is to use as a AP and it worked so charming until about a week ago.

I have 2 Wifi IP cam use the 2.4g channel and the rest devices (laptop, phone, etc) use 5g channel. I'm sure that it should not be related to some bandwidth issues since I was able to have smooth video recording from both IP cams for over 2 months since the original setup. I am still able to use 5g channel to smoothly watch Netflix movies or watch Youtube clips with no noticable lag, Skype video chat works well as well, not to mention surfing the webpages or IMs. The above are all working just fine under 5g. In fact, I tried to test in many different ways, the 2.4g is allowed to connect, assign IP address, but nothing else such as any data flow coming after. 

Searched for the latest firmware V1.0.1.22_1.0.18, updated but no luck. I'm wondering if anyone knows why the 2.4g network just suddenly suspended/mal-functioned? Any suggestion will be appreciated! Hopefully it should not be a hardware issue since the R6900 isn't cheap, and it is only a few months old only... 

Fred

[fredtsai · Accepted solution]

I kind of worked it out what is going on.

I found that the only thing I need to do is to disable the "20/40 MHz Coexistence" and everything just came back to normal. 

I don't know how to put up a picture here, but anyway I tried to use my Dropbox link as below to show you.

Disable 20/40 MHz Coexistence

I think I did the 2.4Ghz channels right by reset the channels with each router/AP, and I'm quite sure that the signal/channel should not have much overlap or interference in between, but after a few hours of trying I still had no luck. 

When I tried to go through all the settings after reset the router to factory default, I found that originally when it is default to be 20/40 MHz. Some articles in other post showing that the system will most likely to use 40 MHz as preferred setting. Then I went back to see all the other router/AP's setting, found that all of my other routers/APs set the frequency width to be 40MHz. I guess that should also means better performance at some level, but unfortunately in my case the wider frequency width from the other routers might just squeeze out the available channels for my R6900.

Anyhow, after disabled the 20/40 MHz Coexistence, the problem seemed to be gone for now. I will stick around and do some more tests and if I got any I will post it here then. 

I guess my issue is not very common in most cases, but hopefully my experience can provide some help to those who needed!!!

[FURRYe38]

Whats the Mfr and model# of the ISP modem the router is connected too? 

What channels are you using on 2.4Ghz. Try 1, 6 or 11.

Set WPA2 and AES only, not mixed. 

Try setting no WPA temporarily to see if any devices connect to the 2.4Ghz radio. Then re-enable WPA2 and AES and test. 

Any other wifi neighbors hear by? How many and what channels are they using? 

[fredtsai]

Thanks for your suggestion FURRYe38, but the channels in 2.4Ghz I tried all 1, 6, and 11 but no good luck. 

I live inside my factory, and I setup the network (both wireless and wired) on my own. I run a canned food factory in Thailand, and pretty much no other neighbor close by around my location. I have wifi access almost everywhere inside my factory, and I am quite sure that there are not so many wifi interefere here as all the wifi signal that I can get is what I configured, and I already use different channels while I install those AP/routers.

I use cisco load balancer RV320 to combine/load blanace 2 ISPs for main source of internet. I know one of the ISP modem is made by Hwawei but the other one is really unknown. I will double check on that and post it here again. 

Back to the setting, I did tried to remove any security and leave it without any password. I was able to connect, but with a very slow speed even standing right beside the router. When I turn the security password on (WPA2 and AES only), the 2.4Ghz network became unstable again. I did tried to change to other password but the situation seems the same. Meanwhile, no matter what I change in configuration, 5Ghz network still flying real fast and stable. 

Well, I am actually at work right now, I will try to do some more test and will post the result here once I get some.

[fredtsai · Accepted solution]

I kind of worked it out what is going on.

I found that the only thing I need to do is to disable the "20/40 MHz Coexistence" and everything just came back to normal. 

I don't know how to put up a picture here, but anyway I tried to use my Dropbox link as below to show you.

Disable 20/40 MHz Coexistence

I think I did the 2.4Ghz channels right by reset the channels with each router/AP, and I'm quite sure that the signal/channel should not have much overlap or interference in between, but after a few hours of trying I still had no luck. 

When I tried to go through all the settings after reset the router to factory default, I found that originally when it is default to be 20/40 MHz. Some articles in other post showing that the system will most likely to use 40 MHz as preferred setting. Then I went back to see all the other router/AP's setting, found that all of my other routers/APs set the frequency width to be 40MHz. I guess that should also means better performance at some level, but unfortunately in my case the wider frequency width from the other routers might just squeeze out the available channels for my R6900.

Anyhow, after disabled the 20/40 MHz Coexistence, the problem seemed to be gone for now. I will stick around and do some more tests and if I got any I will post it here then. 

I guess my issue is not very common in most cases, but hopefully my experience can provide some help to those who needed!!!