IOS14 - Band-steering and jitter

IOS14 - Band-steering and jitter
IOS14 - Band-steering and jitter
2020-10-22 15:39:46 - last edited 2020-10-22 16:17:44
Model: OC200
Hardware Version: V4
Firmware Version: 1.7.0 Build 20200703 Rel.59609

Updated; 

 

A couple of things happened recently 

 

1) People upgraded to IOS14 

2) I updated the controller and devices to the latest firmware (new interface) 

 

Results 

 

IOS Clients behaving funny; keep dropping back to 2.4ghz 

 

IOS Clients 5ghz throughput very poor compared to historic averages. I.e. 70Mbps vs 450Mbps

 

IOS Clients with very high jitter; 15-35ms - likely the cause of slow throughput 

 

 

Investigations 

 

Whitnessed IOS clients keep switching between 5ghz and 2.4ghz. Band steering was not and never has been enabled. Only since the two upgrades (mentioned above) has this behaviour been observed. 

 

Convinced the slow speeds and jitter was due to the IOS devices switching to 2.4ghz randomly. 

 

Some speedtests are max speed still, most are not

 

So i turned off 2.4ghz thinking this will solve the high jitter - sadly it didnt! I am quite shocked 

 

 

So either the high jitter on IOS clients is down to IOS14 or a misconfiguration i have somewhere. 

 

Any ideas? I know Ubiquiti have had some issues with IOS14, but i'm just raising this here in case i missed something, or if its firmware related, the TP-Link team can investigate. 

 

 

p.s. I have methodically tested speeds and stability with laptop devices on exactly the same channel in the same location at the same rough times and all but IOS14 devices are absolutely fine.  

 

I have also very carefully checked for interferance and signal levels, not that anything has changed recently and the 5ghz airwares are clean. 

 

This illustrates the issue, despite it reach a fairly decent speed, this was an isolated test with no other clients, with a connect rate of 800Mbps+ and should theoretically reach 400Mbps / 450Mbps. 

 

 

 

 

 

 

 

0
0
#1
Options
8 Replies
Re:Band Steering - Sticky to 5ghz - Behaviour
2020-10-22 16:01:36

@bp1000,

 

check the RSSI for the 2.4 GHz radio and the 5 GHz radio on your iOS device.

What levels do you measure at the position where flicking between the bands occurs?

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
0
0
#4
Options
Re:Band Steering - Sticky to 5ghz - Behaviour
2020-10-22 16:18:56

@R1D2 

 

-56 dBm at the position of the above speedtest on the 5ghz band. 

 

Thank you 

0
0
#5
Options
Re:Band Steering - Sticky to 5ghz - Behaviour
2020-10-22 17:28:44 - last edited 2020-10-22 17:32:12

@bp1000, and for 2.4 GHz?

 

As for the WiFi sadness of iOS 14 it's no surprise to me. Apple has a long tradition of screwing up their WiFi with every new iOS version. Usually they will provide a fix sometime later.

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
0
0
#6
Options
Re:Band Steering - Sticky to 5ghz - Behaviour
2020-10-22 22:18:43

@R1D2 

 

2.4: I've logged it as -47dB to -57dB 

 

But i've also logged 5ghz rang from -48dB to -56dB 

 

 

I'm not 99% certain this instability is down to these devices erractically swapping from 5Ghz to 2.4Ghz, sometimes so often, it is mid speedtest. This ping pong seems to go back and forth many times. 

 

I made a mistake in my opening post suggesting that i had disabled 2.4ghz and jitter was still happening. I actually realised there was another nearby 2.4ghz AP broadcastign too. 

 

Since then i've turned them all off and running 5ghz exclusively. Every single test has reported <1ms jitter. 

 

So i'm pretty confident the instability is erractic swapping between 2.4ghz and 5ghz. I dont know what is causing this. Wether it is the latest firmware or IOS14. 

 

I've tried enabling band steering but it didnt change anything. 

 

 

 

0
0
#7
Options
Re:Band Steering - Sticky to 5ghz - Behaviour
2020-10-23 05:51:23 - last edited 2020-10-23 05:52:44

@bp1000, I was referring to your question about when to use band steering in a post which you did delete meanwhile.

 

Flipping between frequency bands happen frequently with many devices when the coverage of the 5 GHz band is not equivalent to the 2.4 GHz band.

 

To use band steering (and to avoid roaming requests even if band steering is turned off), the coverage of both bands must be nearly equivalent. Since 5 GHz signals are attenuated more than 2.4 GHz signals, the signal strength in the 5 GHz band should be approx. 6dBm better than the signal strength of the 2.4 GHz radio. If it's worser than this, don't use band steering.

 

If not using band steering, avoid the same SSID for both bands. Otherwise, devices will generate too many (basic) roaming requests. Many IoT devices do so, not only iOS 14.

 

To me, it seems that iOS 14 is more sensitive to such roaming request, but that's just a guess. I use Apple Macs since OS9, but not iPhones except a few ones as test devices for our hotspot systems (and yes, iPhones always have issues in our tests, even after all fixes from Apple have been applied). And with each new iOS release, we have an increasing number of support calls for our hotspots from iPhone users b/c of issues with their WiFi. In the past, every single one of those issues was caused by a lousy handling of the iPhone's WiFi radio in iOS, but not by our hotspots.

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
0
0
#8
Options
Re:Band Steering - Sticky to 5ghz - Behaviour
2020-10-23 09:45:55

@R1D2 

 

Thank you I have In the end separated the SSIDs and therefore won't be using band steering, 

 

I am still observing very strange behaviour with devices ping ponging between APs, now over 5ghz. 
 

I admit that this environment has very few slow/weak spots coverage wise, so some devices might be in range of 2 APs (on different channels) with relatively similar signal strength. I suppose that is what causes the devices to keep rapidly changing their AP of choice. 
 

For example I just moved from one zone to another and saw the device connect to the closest AP, then back to the original then to the closest, then to a completely different one (second closest) before finally settling on the closest. All within 30 seconds. 
 

very bizarre, perhaps this has always happened and I just haven't been looking. 
 

Point being, now I've separated the SSIDs I no longer have this rapid switch between 5 and 2.4, the instability and jitter caused by 2.4 is gone, although still present and unavoidable for 2.4 only clients. I do still have devices rapidly switching between APs but now only on 5ghz. Whilst this happens speeds do fluctuate, but no wild drops or pauses as 2.4 is no longer a factor, until the device settles in the strongest connection. Perhaps this is normal, or maybe ios14 is more sensitive to choosing an AP. It would be interesting to know if this has always been the case or wether the new firmware of ios14 is magnifying the issue. 
 

Im happy to keep SSIDs separate for now, although not ideal. Shame really as it's worked relatively flawlessly for a long time now. 

0
0
#9
Options
Re:Band Steering - Sticky to 5ghz - Behaviour
2020-10-23 10:12:18

@bp1000,

 

you're welcome.

 

You can try to set a lower RSSI limit in »Load Balance« settings to specify at which minimum signal levels clients should be allowed to connect to the EAP.

 

For example I just moved from one zone to another and saw the device connect to the closest AP, then back to the original then to the closest, then to a completely different one (second closest) before finally settling on the closest. All within 30 seconds. 

 

The AP appearing as the physically closest might not be the closest for EM waves and radio signals. If there are reflections or other interferences in a room, a more distant AP could be the better choice for a specific device, while other devices might use certain heuristics to stick at an AP as long as possible. If you want roaming between APs, you can't do much about this.

 

But I would not care which AP my device is connected to, as long as I have network connectivity.

༺ 0100 1101 0010 10ཏ1 0010 0110 1010 1110 ༻
0
0
#10
Options
Re:IOS14 - Band-steering and jitter
2020-10-24 14:54:47

Hi @bp1000,

 

I was having very similar issues!  Unfortunately, I was making a lot of seemingly minor changes at once to my home network and I never did track down the real root cause of the issue.  Then it mysteriously went away.  I also do not use band steering, all of my iOS devices are on 5.8GHz.

 

Where I first noticed it was with SpeedSmart.net.  This benchmark generally gives me the best speeds, but all of a sudden was reporting speeds like 40-70Mbit/sec as you mentioned.  But Ookla Speed Test and Fast.com were "generally normal" though perhaps a bit slower than usual.

 

At first I thought it was something amiss with this one benchmark test.  But the web version of it (vs. iOS) seemed to be working fine.  And it seemed to be working fine (from iOS) via cellular.

 

First I thought it was my new router.  But I switched it back and it seemed to persist.  Then I thought it was a bad network cable / switch -- this may have been a contributing factor for my son (who is hardwired).  Finally I thought it was some change in config/behavior/performance between the older EAP225's I was replacing with new EAP245's.

 

Of course iOS was changing at the same time, too.

 

I know, I know, 10 demerits for changing multiple variables at once.  But with the kids and wife schooling and working from home all day, I only get a brief window from 11:30pm until I go to bed to make and test changes.

 

It's strange though I was on iOS14 for at least a week before making these changes and didn't see any issues.  I don't know if it was 14.01 that did it, or something else.

 

-Jonathan

 

 

0
0
#11
Options
Related Articles