Please disable my WiFi 2.4 channel “optimisation”

[prawlin]

I tagged onto a similar thread, but then I suddenly remembered historically that is taboo on these weird TT forums. So before I get chastised by the net police, I’m starting my own thread here.

I have an issue when using my expensive Sennheiser digital cordless headphones. I had the issue a long time and only recently realised what is going on.  The headphone transmitter and receivers unfortunately operate slap in the middle of the shared WiFi 2.4 band (but not using actual WiFi protocol). They use a proprietary FHSS system. I’ve learned that when my router is on Ch6 it makes the headphones frequently but intermittently drop out. If I set my Sagem TT router to channel 13, all is good with all my many (2.4 only) WiFi devices and the headphones operate perfectly. I can prove this with my RF spectrum analyser. I have set many of my connected devices to use only 5GHz WiFi. If I could disable WiFi 2.4 I would do. However, many of my devices won’t support 5GHz, so I have to leave it on.

Very annoyingly the router will switch itself back to Ch6 after a day or two. 
I’ve read on these forums that this is called Auto optimisation, and it can only be turned off by TT support. So PLEASE turn it off on my TT router ASAP!  Thank you and regards. Peter (long term very loyal TT customer)

[prawlin]

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@Debbie-TalkTalk wrote:

Hi Peter

Thanks for your reply.

Our Products Team have asked us not to switch off WIFI optimisation now.

 I can ask our faults escalation team to take a look at this for you. Would you like me to ask the team to contact you to discuss this further?

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Aha. Now I understand. Thanks for that. 
Well if it is likely to end up with my specific request being fulfilled then yes please do that.

However, if I’m just going to get an educational lecture as to why it’s not advisable or permitted to switch it off, and then still not doing it then frankly there is no point as it is wasting everyone’s time. That would be a very disappointing outcome, as the router has been wonderfully reliable in all other respects. This compulsory auto Channel switching/optimisation is a real PITA for me. It probably works well for most scenarios but in my situation it is so very annoying. 

I am happy to discuss it via Email, SMS, or this forum but I prefer not to receive phone calls if possible please.

Thanks again Debbie.  Peter

[Debbie-TalkTalk]

Hi Peter

Thanks for your reply.

Our Products Team have asked us not to switch off WIFI optimisation now.

 I can ask our faults escalation team to take a look at this for you. Would you like me to ask the team to contact you to discuss this further?

[prawlin]

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@Debbie-TalkTalk wrote:

Hi @prawlin 

We are unable to switch off WIFI optimisation.

Have you recently rebooted the router?

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Hi Debbie

I only reboot it occasionally, if when things fail to connect which is rare. Last time was a few weeks ago. Are you suggesting I should reboot it now, and will this then allow you to turn off the optimisation as per my request?

I don't understand why you say the WiFi optimisation cannot be switched off as I request? I see just a few weeks ago, you yourself switched it off for another customer and it fixed his (admittedly quite different) issue here see message #9…….

https://community.talktalk.co.uk/t5/Broadband/WIFI-OPTIMISATION/td-p/3034690

I know my own issue is as a result of my Sennheiser headphones design trying to use the same frequency range as WiFi 2.4GHz uses hence why the headphones malfunction. However, I have also proven by manually changing the WiFi channel the router uses I can fix this issue completely. That is until this nuisance optimisation thing kicks in again and changes my WiFi back to Channel6 (which is the worst possible channel for my situation!)  Please can you switch off my WiFi optimisation as you did for the other customer recently? That is all I’m asking for. Then I will have full control over the WiFi channel that my router uses. 

If you still can’t do this for me, then please explain to me why not as you have clearly done it very recently it for other customers in order to solve their own issues.

Thank You. Peter

[KeithFrench]

From the way that I understand this problem @Debbie-TalkTalk, the headphones seem to be using a part of the 2.4GHz RF spectrum (not WiFi) that the 802.11 WiFi also uses. Therefore this is not Wi-Fi interference, but the two services are conflicting with each other. I think from what the OP has said, things work OK when he has control of the WiFi channels. However, this is a complex situation & I do not know the other RF usage from a technical standpoint to help any further on this.

[Debbie-TalkTalk]

Hi Prawlin and Keith

Are all other devices working ok?

[KeithFrench]

Hi @prawlin 

I really do not see what TalkTalk can do about this, as it does seem to be a problem with these headphones.

[Debbie-TalkTalk]

Hi @prawlin 

We are unable to switch off WIFI optimisation.

Have you recently rebooted the router?

[prawlin]

The headphones do not use WiFi protocol Keith. SSID is a WiFi protocol thing is it not?
I don’t know anything about the proprietary Sennheiser digital protocol. I assume it is not even published anywhere. 

It uses a spread spectrum FHSS (bidirectional) broadcast from the Transmitter to the headsets that just happens to use the same licence free 2.4GHz ISM band. As such, interference between the very many users of the band is to be expected. WiFi is just one of the many users of the same 2.4GHz radio band unfortunately.  As I said earlier, Sennheiser made a poor choice of radio bands to use with 2.4GHz. It’s pretty obvious many user will want to use these headphones in a home situation where WiFi will always be present. Maybe they thought their protocol was sufficiently robust so to tolerate some packet losses when WiFi is present in the near vicinity? They got that bit wrong, clearly.  

It would have been much better if the HP did actually use WiFi linked via the router, then they could coexist with all the other WiFi networked stuff, and this interference would not be an issue. 

https://en.wikipedia.org/wiki/ISM_radio_band

https://en.wikipedia.org/wiki/2.4_GHz_radio_use

No sign of the TT CS yet? Though I expect they will have a backlog after the bank holiday weekend. I see the router pops up on a different Channel 1,6,11 every time I look. I can get an evenings headphone use if I set router to C13. Next day it’s always moved to one of the others, usually C6 which is the worst one for my headphones to co exist with. C1 or C11 is better but C13 is best for me.  Cheers. Peter

[KeithFrench]

Do the headphones broadcast out their own SSID then?

[prawlin]

Ok, just for technical interest ……..

Router on C6 and HP filling band!Router alone on C6 no HPRouter C1 yell. C6 green. C13 purple.3 router chans yell,green, purple. HP on Red

[KeithFrench]

Yes just use the Include Photos button on the toolbar.

[prawlin]

Hi Keith. 
Thanks for the suggestion. It is a good one. However my router is already on 20MHz bandwidth (and has been for years).

It is the headphones that are really the cause of this issue. A poor RF design choice IMHO.  They use a strong  frequency hopping system which literally operates across almost the entire 2.4 band. It centres on CH6 but some packets can be seen within Ch1 and Ch11 pass band on my spectrum analyser. Ch13 is *just* clear of the HP transmissions but with zero guard band between the HP signal envelope and CH13. There is no possibility to change anything on the headphones. My Router is a bit closer to me at my usual listening HP position than the HP Tx is. This obviously won’t help the situation but I can’t really change that easily.

I appreciate your helpful input suggestions, but I’m certain disabling the auto ch selection will resolve it for me. (PS I’m a retired electronics engineer so do have a reasonable understanding of this stuff). I might try to capture some analyser screen shots just for interest if I get some time. It’s astonishing to see how the HP packets totally obliterate the 2.4 WiFi band. It’s amazing that the WiFi appears to work normally even on Ch6 whilst the headphones are switched on. Presumably WiFi has really great error correction algorithms that deal with the inevitable packet burst collisions.  Will this forum allow image attachments ?

I use the headphones literally on a daily basis for late night TV viewing. My walls are thin and my neighbours retire early. I don’t want to disturb them. Also, my hearing isn’t as good as it used to be so headphone listening gives me a big clarity boost. The Sennheiser HDR 185 give me fantastic quality audio performance throughout the house and garden (when they’re not being zapped by my router!). 

Thanks again. Peter

[KeithFrench]

Hi @prawlin 

In light of what you said on the other thread:-

"Yes I know about the old overlapping channels rule. But Though moving from Ch6 to Ch11 helps to reduce my interference to my Sennheiser headphones However it does not eliminate my problem. The Sennheiser uses very wide FHSS occupying much of the 2.4G band, centred around Ch6! but still spilling into C1 and C11. It just clears C13. Hence why it’s my preference in this case. 

I tried Ch11 during my extensive testing and it still reverts to Ch6 anyway.  So either way I still need the compulsory optimisation turning off on my router. I think it’s ridiculous that I can’t turn off this “I know better than you do” auto optimisation feature. Heck I can change a thousand other potentially destructive settings myself so why not this one?"

This sounds to me like the router is set to allow a 40MHz channel bandwidth within the 2.4GHz band, which is another definite no, no. This is very counterproductive, as a 40MHz channel uses up 9 out of the 11 possible channels. This will cause you to have a dramatic loss of performance, not to mention any other nearby networks, as it will cause them massive interference as well.

Please set your channel bandwidth in this band to 20MHz only. It is not your cordless headphones that are mandating this bandwidth, it is totally the router that is in charge here. Alas WiFi Optimisation in my testing does not enforce 20MHz only, so you will need to change this yourself.

[prawlin]

Hi @Divsec 
@Thanks for that. I can’t wait😉 I’ve suffered this super annoying interference issue for a very long time (years!). I even bought a second Sennheiser headphone set as I thought they were faulty! Then I recently bought a spectrum analyser and finally realised what’s actually going on. A Eureka moment indeed. Now I’m kicking myself for not sussing this out somewhat earlier. 

Peter

[Divsec]

Hi @prawlin your post has been escalated and you should hear Tuesday due to holidays.