2.4 ghz band intermittent poor throughput

[alexmuk]

Hi guys,

I've been lurking around for a while and decided to ask some expertise.

I've had an issue where my 2.4ghz speeds intermittently drop sometimes as low as 1meg, (this is connected to a 30meg cable connection), the 5ghz band is fine however which suprised me.

Sometimes the issue will happen even in the same room as the router, but much more likely to happen at a distance. I know the router is capable of the speed, just intermittently.

I'm currently using a Netgear N7000
But I had the same problem with the ASUS R66U and the WNDR3700 netgear
The problem is especially noticeable On mobile device namely iphone 5/5s

The ac link is absolutely blistering on my macbook also and the dlna server is adequate, just this silly slow speed drop on 2.4ghz

I've tried changing channels, enabling and disabling n-only modes, played with tX power, updated firmware, moving the antenna around (not sure what way to move them if I want better speeds upstairs)

The signal strength is actually is showing to be in the 50's pretty much constantly with the absolute worst reading at -60, which confuses me even more!

I can't think of anything interfering with it, I've tried it with no one else connected also, but just can't understand why 5ghz works fine and 2.4 doesn't !!

Spending near £200 on a home router with around 8 devices including mobile ones i thought is solve the problem !

Is there anything you guys can suggest, quite clearly signal strength doesn't equal throughput.

If there is any more info you need, please be sure to let me know. Reluctant to change antennas on it as unsure of the compatability, what with this ones insane beam forming and all that.

Thanks so much

 

[stevech]

WiFi's radio channels are a shared medium!
Hypothesis: A neighbor on/near your chosen WiFi channel is occasionally using a lot of air time (available capacity).
Try changing the router to use a different channel among ideally 1,6, 11. If you can guess which of the fairly strong neighbor-SSIDs near your channel is using a lot of airtime for streaming HD (or whatever), try to avoid that SSID's channel +/-3.

Othewise, it might be the client device not able to get a good signal TO the router for the uplink ACKs and other traffic.

 

[alexmuk]

WiFi's radio channels are a shared medium!
Hypothesis: A neighbor on/near your chosen WiFi channel is occasionally using a lot of air time (available capacity).
Try changing the router to use a different channel among ideally 1,6, 11. If you can guess which of the fairly strong neighbor-SSIDs near your channel is using a lot of airtime for streaming HD (or whatever), try to avoid that SSID's channel +/-3.

Othewise, it might be the client device not able to get a good signal TO the router for the uplink ACKs and other traffic.

Hi Steve, thanks for your reply.
I've chosen the least congested channels (it happens to be channel 1), there is one SSID in the area that shows -87dB on that channel so I wouldn't have thought it's that. And experimented with other channels, although I can see your rationale, since my 5ghz has no problem- it surely can't be a router positioning problem as everyone knows 5ghz considering considerably more issues with range and line of sight.


The speed loss is noticeable accross all the devices that use the 2.4ghz band, I'm just trying to think what to do for the best. I do have a WNDR3400 knocking around, perhaps use that as an AP upstairs, it just seems such a waste after buying such an expensive and supposedly amazing router to try and cure my ailments.

Also, while I have a person on hand, - if I change my region to North America, other than adding extra channels, does this make any difference to performance ?

 

[Mick243]

It's not just other wifi that can cause interference, it can be cordless phones, baby monitors, remote controll toys, garage door openers, dodgy microwave ovens just to name a few, and none of these show up on a network scanner such as inssider.

 

[stevech]

Above posting, true. Esp. baby monitors. Not many 2.4GHz cordless phones now since DECT.

But again, OP: the number of SSIDs is not important. It may be that ten SSIDs all near channel 11 are lightly used but ONE SSID at channel 3 is the airtime hog!

 

[alexmuk]

Again- thanks for your time guys, I did understand that there are devices that interfere other than other wifi networks.

I just wish for the life of me there was a way to find out just which! There's nothing in my house that is doing it, that I'm 99% certain, because I've not gotten anything new other than an xbox upstairs in the house. I do live with a house either side of me - a mid terrace house.

So perhaps something in there is intermittently causing the speed drops - the devices that do cause the interference- do they cause it generally on all channels of the 2.4ghz band in your experience ? ?

 

[alexmuk]

Also- I forgot to ask, is there much of a bandwidth loss, when using another router as an AP?

There is a couple of legacy devices that connect, the potential AP is a WNDR3400

If setup correctly, will it literally just be an extra wireless radio fully integrated to the current network ? Just I still want to be able to access NAS/DLNA Server fully from the AP when needed.

 

[Mick243]

Depending on the interfering device, yes, some can wipe out the whole band. Bear in mind, it's an unlicensed band with lots of things transmitting in it, not all of which use the same frequencies or bandwidths, and some are much more powerful.

As for a second AP, if done right won't cause any throughput loss.

As for legacy devices, if you use a B device on a G network, it slows everyone down to B speeds... I think it works the same for N.... So instead of trying to speed things up with faster AP's, it is often better to replace slower legacy devices that hold everything back - have a read of the article about "add don't replace when switching to N". So, in your case, having 2 AP's available to use, stick all the slower legacy devices on one, and all of your faster newer devices on the other, on different channels with different SSIDs

 

[alexmuk]

Depending on the interfering device, yes, some can wipe out the whole band. Bear in mind, it's an unlicensed band with lots of things transmitting in it, not all of which use the same frequencies or bandwidths, and some are much more powerful.

As for a second AP, if done right won't cause any throughput loss.

As for legacy devices, if you use a B device on a G network, it slows everyone down to B speeds... I think it works the same for N.... So instead of trying to speed things up with faster AP's, it is often better to replace slower legacy devices that hold everything back - have a read of the article about "add don't replace when switching to N". So, in your case, having 2 AP's available to use, stick all the slower legacy devices on one, and all of your faster newer devices on the other, on different channels with different SSIDs

Thanks for your input, this does seem like a logical way to do it, although my cable connection is 50meg so as long as I can get as close to that as possible, then I'm okay.(on the 2.4ghz band)

There is just a couple of G Devices on my network. I'm guessing it probably wouldn't be sensible to stick my WNDR3400 in a boiler cupboard, so I'm going to have to think carefully about position, I just wish I was good at DIY, I'd trace the cables through the wall and make a nice tidy AP.

 

[azazel1024]

They don't reduce the speed of everything else to B or G. What is generally happening is airtime sharing, CDMA. Collision Detection Multiple Access. Its how Wifi works.

So what the router is doing is sharing airtime across client devices.

If you have one at 11Mbps, one at 54Mbps and one at 300Mbps, depending on how well thought out the router firmware is, what will happen is that the router will assign 1/3rd airtime to the B client, 1/3rd to the G client and 1/3rd to the N client.

So that B client is going to be cut down to 3.6Mbps, the G client to 17.8 and the N client to 100Mbps. That is, if things were maybe, possibly being shared correctly. A lot of routers don't/won't. So what might happen is that the router will assign airtime for 10 packets to the B, 10 packets to the G and 10 packets to the N client. Well, the B client is WAYYYYY slower than the others, so its 10 packets end up actually taking WAY more of the airtime. So the B client might actually be "stealing" 80+% of the Tx/Rx time because it is going so slow, even though the router is round robining the packets to/from each client.

This is in large part why older clients have such a huge impact on newer standards. Having seperate APs for older clients has less overall bandwidth problems because the routers aren't going to coordinate airtime (there isn't hidden node issues though, but CDMA works somewhat different when it is two seperate base stations operation than one. There is going to be some more stepping on each others transmission and receives, but when mixing in older clients, this is generally more beneficial for newer clients than airtime sharing).

So if you have an 11b client doing a lot of Tx/Rx on an 11n network, it might knock 50-80% off the speed of the 11n client with airtime sharing, but the 11b client might only see a 10-20% reduction. Where as, if you have that 11b client on its own access point and the 11n client on its own, interference is going to cause some problems, but in all likelihood what you'll see is maybe only a modest 10-30% reduction in speed on the 11n AND 11b clients.

As for what is causing the massive drop in 2.4Ghz throughput, is it consistent across ALL clients? Or is it just one or two causing it? I'd still play with channels, just because you are using the least congested in regards to other visible networks doesn't mean it is the least used or the one that has the least interference.

Most baby monitors are on 900MHz by the by, not 2.4GHz.

Also is the interference regular? For example, does it occur every 10 seconds for a second? Once a minute for a second? Every 10 minutes for a minute? Any kind of pattern to it? If there is a pattern I'd suspect it is an issue with an intermitent and regular emitter. Maybe an electric smart meter that is stupidly on 2.4GHz and transmitting at really high power or something.

You could always try the other router in access point mode and see if there are issues using its 2.4GHz radios. If no issues, I'd assume it is an issue with you current router.

 

[jlake]

Most people have the best luck on 2.4 ghz when they change the channel width from auto to "20 MHz".

 

[alexmuk]

They don't reduce the speed of everything else to B or G. What is generally happening is airtime sharing, CDMA. Collision Detection Multiple Access. Its how Wifi works.

So what the router is doing is sharing airtime across client devices.

If you have one at 11Mbps, one at 54Mbps and one at 300Mbps, depending on how well thought out the router firmware is, what will happen is that the router will assign 1/3rd airtime to the B client, 1/3rd to the G client and 1/3rd to the N client.

So that B client is going to be cut down to 3.6Mbps, the G client to 17.8 and the N client to 100Mbps. That is, if things were maybe, possibly being shared correctly. A lot of routers don't/won't. So what might happen is that the router will assign airtime for 10 packets to the B, 10 packets to the G and 10 packets to the N client. Well, the B client is WAYYYYY slower than the others, so its 10 packets end up actually taking WAY more of the airtime. So the B client might actually be "stealing" 80+% of the Tx/Rx time because it is going so slow, even though the router is round robining the packets to/from each client.

This is in large part why older clients have such a huge impact on newer standards. Having seperate APs for older clients has less overall bandwidth problems because the routers aren't going to coordinate airtime (there isn't hidden node issues though, but CDMA works somewhat different when it is two seperate base stations operation than one. There is going to be some more stepping on each others transmission and receives, but when mixing in older clients, this is generally more beneficial for newer clients than airtime sharing).

So if you have an 11b client doing a lot of Tx/Rx on an 11n network, it might knock 50-80% off the speed of the 11n client with airtime sharing, but the 11b client might only see a 10-20% reduction. Where as, if you have that 11b client on its own access point and the 11n client on its own, interference is going to cause some problems, but in all likelihood what you'll see is maybe only a modest 10-30% reduction in speed on the 11n AND 11b clients.

As for what is causing the massive drop in 2.4Ghz throughput, is it consistent across ALL clients? Or is it just one or two causing it? I'd still play with channels, just because you are using the least congested in regards to other visible networks doesn't mean it is the least used or the one that has the least interference.

Most baby monitors are on 900MHz by the by, not 2.4GHz.

Also is the interference regular? For example, does it occur every 10 seconds for a second? Once a minute for a second? Every 10 minutes for a minute? Any kind of pattern to it? If there is a pattern I'd suspect it is an issue with an intermitent and regular emitter. Maybe an electric smart meter that is stupidly on 2.4GHz and transmitting at really high power or something.

You could always try the other router in access point mode and see if there are issues using its 2.4GHz radios. If no issues, I'd assume it is an issue with you current router.

I have one G device connecting to the network an old xbox adaptor, but the problem persists even when this is not connected to the network, the speed drops SEEM to be sporadic with no set pattern like you suggested could happen.

It does indeed seem to be all clients connected to the 2.4ghz band, but mobile devices are affected more so than say the macbook when connected. I've tried to change to every different channel I can and the result is still the same. Nothing has changed in my home, I can't say the same for my neighbours though of course.

I don't want blistering speeds, I just want a consistent connection for my 50meg cable running into the router.

Changing channel bandwidth to 20mhz only didn't help either.
Tearing my hair out, it's only a small 3 bedroom 2 storey house, not a luxury mansion (although the router I bought seems to sell itself for such!)

 

[sfx2000]

WiFi's radio channels are a shared medium!
Hypothesis: A neighbor on/near your chosen WiFi channel is occasionally using a lot of air time (available capacity).
Try changing the router to use a different channel among ideally 1,6, 11. If you can guess which of the fairly strong neighbor-SSIDs near your channel is using a lot of airtime for streaming HD (or whatever), try to avoid that SSID's channel +/-3.

Othewise, it might be the client device not able to get a good signal TO the router for the uplink ACKs and other traffic.

I totally agree here - WiFi is a shared medium - and if bandwidth takes a hit in the evening - well, between streaming media (NetFlix, Hulu) and just more traffic..

Both your client and the AP - they listen for free air time, or at least a best attempt before transmitting - if you're in an area where there are many wifi networks, then yes, it's going to take a hit if adjacent networks are busy.

One thing you can try - if your router has an radio mode selection - e.g. 802.11n Only or Mixed Mode - try using Mixed Mode - less overhead...

The regular guidance also applies - start at channel 1, move to 11, and then down to 6 in 2.4Ghz...

 

[alexmuk]

Thanks for the suggestion, bandwidth continues to sporadically drop. Speeds across the internal network seem less affected oddly, it's WAN mainly on 2.4 ghz and very much more pronounced on iPhones, that's where the most crippling speeds of sub 1 meg tend to occur for me.

I've tried setting to "upto 600mbps" and also tried enabling disabling 20/40 coexistence, still persistent!

Tempted to dd-wrt it, as the firmware on the router is a fairly new release so unsure if perhaps it's a buggy build or not, but since it did it on other routers, it does indeed point to external interference of some kind.

The cable guy (not Jim Carey) came out whilst fixing the phone line, and the signal levels are perfect coming into the modem, and he said I was "booming out" with my wifi signal.

Ultimately I'm going to have to try and change the physical location of the router to See if that offers any respite. Makes me wish I had an EMP to take my neighbours offline lol, I was here first dammit !!! There's only 5 SSID's I readily pick up in my area, only two of which are strong ish signals.

What about channel 13, if I were to theoretically change my region from Europe to North America ?

 

[stevech]

you've tried channels 1, 6 and/or 11

No. America has fewer channels (on the high end) than the EU. I would not alter the regulatory region settings for fear of interfering with other radio services.

 

[RogerSC]

You want to leave "20/40MHz. coexistence" enabled, that forces you to 20MHz. bandwidth on the R7000 if you're in a crowded area. If your problem is interference, then making your signal wider doesn't seem like it's going to help as much as making it narrower, and avoiding the interference (if possible).

 

[alexmuk]

You want to leave "20/40MHz. coexistence" enabled, that forces you to 20MHz. bandwidth on the R7000 if you're in a crowded area. If your problem is interference, then making your signal wider doesn't seem like it's going to help as much as making it narrower, and avoiding the interference (if possible).

Noted, I see the rationale behind this clearly.

I noted that the speeds were still inconsistent at 2am this morning when every light was off in both the houses next door to me, and every device in my house was off, other than my iPhone @ 2.4ghz and macbook @5ghz

So that narrows it down a little further and seems to suggest, that it is something autonomous that is causing the problem, what though remains to be seen.

How long can a piece of Ethernet cable be between the cable modem and the router itself, before noteable drops are recorded by the way? Just thinking in way of relocating the router to the most central point it can possibly be in the house, which will involve putting up a shelf of some sort and will need around 15ft of cable if my guesswork is correct

 

[L&LD]

With a good quality cable; 100M.