Sky Hub "Auto" channel selection is broken

I live in an area with no other wireless networks visible. I have two Sky Hubs (SR101) sitting next to each other. The wireless channel on both Hubs is set to "Auto".

If I turn one on after the other, the second Hub always transmits on channel 1, even though the first Hub already transmits on channel 1 and all other channels are unused.

Hub documentation says: "Sky assign different channels to your wireless network randomly to minimise interference with other networks in your area. It should not be necessary to change the wireless channel unless you notice interference problems from another nearby wireless network so Sky recommend leaving this set to auto"

Even if the channel selection is "random" as the documentation suggests, it always selects channel 1. I could manually set the channel on the second hub to 6 or 11, but this defeats the point of having an auto channel selector.

Clearly the "Auto" setting on the SR101 Hub just sets the channel to 1 regardless of interference from other networks and is never randomised either, so the "Auto" function in the Hub appears to be broken.

Considering how important it is to have wireless using the most uncongested frequency for performance, especially in the congested 2.4 Ghz area which these Hubs operate, a bug such as this potentially is slowing down a lot of wireless connections.

A visual example might help: http://s7.postimg.org/j80itwwvv/wifi.png

Top two networks are my Hubs sitting together, both set to auto channel selection. Bottom network is a neighbour's (very weak signal).

The break in the second graph was me rebooting the second Hub. The router came back on the same congested channel (1). First hub was on channel 1 all the time.

When no traffic multiple wifi on the same chanel is not a massive issue.

Does any channel hoping occur if you start a video stream on both for example?

In reply to a post by MrSaffron:

When no traffic multiple wifi on the same chanel is not a massive issue.

The second Hub knows (or should know) that channel 1 is already in use by the first Hub. Even if the wifi link is idle at the time of connection (which it was), that's not to say it will be for the lifetime of the connection.

So there's no justification for "auto" not to take channel 6 or 11 since there is less chance of post-connection congestion.

Channel hoping would produce amusing results.

And could explain some of the buffering moans people have

I agree

WiFi is really only good for web browsing and maybe audio streaming.

It's not that big of a deal using the same channel for routers. It's other things that are analog that cause major issues on the spectrum. I mean ideally it should choose another channel as they're free but performance wise it's not the end of the world.

I've always found my sky hubs defaulted to channel 6 or 11 as the neighbour uses 1 always though.

In reply to a post by ukhardy07:

I mean ideally it should choose another channel as they're free but performance wise it's not the end of the world.

I agree it's not the end of the world, that would be slightly over-dramatic.

But with the amount of wireless routers around now, I feel that the "auto" channel setting is something router manufacturers should get right.

I agree with you however realistically auto channel section works like this.

The router instantly tries for channel 1. If there's some big interference it will jump to 6. In some extreme almost winning the lottery chances it may even make a wild jump onto channel 11. That's just my experience of auto channel selection. Of course some people swear it works brilliantly.

Even that would be better than what my hub is doing, since it selects channel 1 even though it's sitting next to another hub on channel 1.

If anyone's interested, it's an SR101 with firmware 1.15n.3591.R

So, you click on a video to watch. The router decides to switch channels and your PC loses connection. Your PC now tries to connect to your neighbour's BT Fon, but you will need to open your browser to type your login credentials - game over.
I don't think that would get past the Wifi Consortium QA testing.

The funny thing is, my older D-Link Sky router behaves exactly as desired: when set to auto it picks the least congested channel. The newer Hubs seem to have taken a backwards step.

Which raises the fun game of when should a router switch channels?

The latest SR102 hub seems ok. Mine has taken channel 6, it's sat right next to a BT Hub 3 on channel 1.

In reply to a post by CJ8:

The latest SR102 hub seems ok. Mine has taken channel 6, it's sat right next to a BT Hub 3 on channel 1.

I'd imagine it's a firmware issue so hopefully the SR101 can be corrected.

Hi Oliver. I trust you have manually set the Wi-Fi channels?

Probably best to choose channel 1 for one and Chanel 12 for the other so that they are at extreme ends of the spectrum. This should give you the least interference possible.

In reply to a post by PS123:

Hi Oliver. I trust you have manually set the Wi-Fi channels?

As I say, I have enough technical knowledge to scan the wifi channels with inssider and select an unused channel manually. The problem is that

1) I would like the router to do this for me every time it boots and

2) The vast majority of Sky customers will not do this, and shouldn't have to

The "auto" setting needs fixing.

Generally WiFi monitors such as inSSIDer etc, display only the WiFi transmissions in the immediate area.

However, there may be a NON-WiFi device radiating in other parts if the WiFi spectrum, thus your two Hubs staying on Channel 1.

Typical sources are Micro-Wave Cookers (intermittent obviously), Baby Monitors (more continuous), Plasma TV sets, etc.


To determine if anything of that sort is causing the "fixed" selection, you would have to ensure that all such devices are switched off; or alternatively use a Spectrum Analyser covering the WiFi Channels, 2.4 MHz and 5.0 MHz.

Some of the interference sources may be working at a much lower frequency, say 240 MHz; BUT producing harmonics, in this example, the 10th harmonic at 10*240MHz = 2,400 MHz = 2.4 GHz.

Generally the Harmonic content drops off rapidly in power at its source, so the 10th Harmonic would be at a very low power level; but WiFi generally works at very low power levels as well, so easily "drowned" by interference.

If WiFi was not at such low power levels, it could cause problems the other way; and also quickly discharge the batteries on portable devices.

Are you suggesting the Sky router has a spectrum analyser that can detect non-wifi radiation?

Whilst I agree inssider will only display certain types of interference, I cannot imagine that any of those sources is worse than a second wifi hub standing right next to the first, on the same channel.

I don't have the equipment to prove it, it's just what I believe.

In reply to a post by BatBoy:

Are you suggesting the Sky router has a spectrum analyser that can detect non-wifi radiation?

Yeah, that would seem unlikely. At the most I would expect routers to run something like "iwlist scan" to determine the likely sources of interference.

Evening Batboy et al

No, I am NOT suggesting that routers act as Spectrum Analysers.

They simply react to the presence of RF power that would swamp their own efforts; and look for a quiet/er channel within the WiFi allocation.


Think of persons such as Radio Amateurs. Before transmitting, they check using their receivers, within the allocated spectrum such as the "20 Metre Band" for a quiet/er spot, tune their transmitter (Tx) to that frequency, either manually or by changing crystals, then go on the air.

They may change frequency several times during a session, as other transmissions or noise appear and disappear.

The Routers effectively do a very similar thing with WiFi; but are fully automated, particularly when set to the "Auto" mode.


I suggest that you search for "frequency hopping", "Hedy Lamarr" (WW2 Film Star and Mathematician).

WiFi technology works in a very similar manner!

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

A starter-
https://en.wikipedia.org/wiki/Hedy_Lamarr


Thus the OP's Routers may be sticking to Ch 1, because the rest of the 2.4 Gb WiFi allocation is saturated with "noise"; but do not have the means of conveying this to him as a user.

Basic inSSIDer only displays what it recognises as being WiFi transmissions. Check on the Metageek site for the extension converting it to a Spectrum Analyser, called "Chanalyser".

I prefer the simpler explanation that it's broke

Evening Oliver

inSSIDer in itself only didplays the active WiFi circuits it can decipher.

It does not display in any manner, any sources of interference, whether coherent (intelligent transmissions) or incoherent (noise etc).

Take a look at Chanalyser and other extensions of inSSIDer-

http://www.metageek.net/support/downloads/

The site has some very interesting documents.

In reply to a post by eckiedoo:

It does not display in any manner, any sources of interference, whether coherent (intelligent transmissions) or incoherent (noise etc).

Can you be sure that the Hub is scanning for non wifi interference when choosing a channel?

Can you be sure that the amount of non-wifi interference in my house on channels other than 1 exceeds the amount generated by a Sky Hub set to channel 1 literally touching the second Hub set to "auto"?

Yes, it possibly is - BUT "if it ain't broke" then one would expect any other replacement Router/s to similarly stay on Channel 1.

That would be one way of establishing what the problem, if any, is.

I wonder if he moved the Routers as far apart as he reasonably can, would this help clarify the situation.

===========================

My own Brightbox Router generally operates on Ch 6 & 11, including the secondary circuit I have set up for visitors. Both show 300 Mbps "bandwidth".

The Router is set to "Auto" Channel Selection.

Often when monitored on inSSIDer, I see either of those two circuits independently and separately cutting back to Ch 6 only; and on a rare occasion, to Ch 11 only.

Occasionally those moves can be (almost) "simultaneously; but generally are widely separated n time. Minutes etc.

Occasionally I see other double channel (eg Ch 6 & 11) Routers switching down to Ch 6 only. None of them appear to have a Visitors/Secondary Channel set up.

There are others operating on the other Channels, generally Ch 1 and 11.

One of the other Double Channel Routers has a "bandwidth" of 274 Mbps, the majority of the rest whether double or single Channel are at 144 Mbps, with a few at 54 Mbps.

In reply to a post by eckiedoo:

Yes, it possibly is - BUT "if it ain't broke" then one would expect any other replacement Router/s to similarly stay on Channel 1.

That would be one way of establishing what the problem, if any, is.

I wonder if he moved the Routers as far apart as he reasonably can, would this help clarify the situation.

I though it already has been clarified?

In reply to a post by Oliver341:

The funny thing is, my older D-Link Sky router behaves exactly as desired: when set to auto it picks the least congested channel. The newer Hubs seem to have taken a backwards step.

"Can you be sure that the Hub is scanning for non wifi interference when choosing a channel?"

That is a basic function of their design, to make best use of the available spectrum.

If course, it could be that one or t'other or both are faulty in that aspect.

==========================

"Can you be sure that the amount of non-wifi interference in my house on channels other than 1 exceeds the amount generated by a Sky Hub set to channel 1 literally touching the second Hub set to "auto"?"

Without visiting your house with an array of monitoring equipment and special test equipment, NOBODY CAN BE SURE OF THE CAUSE,.

Try moving the Routers as far apart as possible.

If you have a "spare" laptop or notebook or netbook available, download CONNECTIFY or similar software which would allow that PC to act as a WiFi Hotspot, ie similar to the Routers.

With your SKY Routers widely separated take that Hotspot PC close to each in turn, switching the CONNECTIFY PC across Ch 1 to 13 progressively, to see if that has any effect.

If for example, one SKY Router remains on Ch 1 whilst the other moves automatically away from the Hotspot Channel, then the one that stays on Ch 1 is likely to be faulty; but if both react in a similar manner, the it is likely that both are functioning properly.

========================

If you download inSSIDer and monitor your SKY Routers, you will see that when they are nit handling traffic, their Transmission Powers remains low, typically about -45 db in the case of my Router.

When actually handling traffic, ie actually Downloading particularly, the Power Levels will increase to in my case, around -11db.

The lower the Power Level (eg -45 db), the less chance of interference.

If your two Routers are not Downloading significant streams of traffic simultaneously, then they are unlikely to cause to interference with one another, hence remaining on the same channel.

So that give you the basis for another test.

With them close together/touching, try downloading on both simultaneously, a film ir TBB's bigger Test Files, whilst monitoring on inSSIDer, to see if Channel Switching occurs.

==================================

As you will appreciate, WiFi technically is far from simple.

It also could be that the design of the newer routers is "more robust"; and can handle worsening SNRs.

As more and more devices use WiFi, technically this is an essential improvement.

Intelligent - Refrigerators, CH Systems, Speaker connections etc etc.
(Dfficult to keep up with them all!)

It could also be simply different design parameters, chip sets etc.

In reply to a post by eckiedoo:

It also could be that the design of the newer routers is "more robust"; and can handle worsening SNRs.

Oh, so not this then?

one would expect any other replacement Router/s to similarly stay on Channel 1.

We seem to be in agreement, unless I am misinterpreting your posting.

In reply to a post by BatBoy:

I prefer the simpler explanation that it's broke

If the likes of enterprise WAPs like Rukus and whatever can't get auto-channel selection working properly then it does not surprise me the Sky Hub can't...

I agree it's broke.