Massive Drop in Sync Speed

Hey All,

I am after a bit of advice on how i could possibly proceed with this problem. I have had my ADSL2+ since June last year. Its always sync'd at a minimum of 12Mbits and normally around 14Mbits.

Yesterday - all of a sudden it drops and will now only sync at around 5Mbits.

My ISP (Freeola) have asked me to do the normal stuff to check things - Basically i have been able to change everything from the micofilter to the router and even to a different PC. No matter what i do the sync speed remains at a very low 5mbits.

These are my current line stats:

ADSL Link Downstream Upstream
Connection Speed 5706 kbps 440 kbps
Line Attenuation 23.5 db 10.5 db
Noise Margin 6.0 db 12.5 db

Considering that for over 12 months its been solid at between 12 and 14 Mbits, and all of a sudden dropping to 5Mbits - They are telling me this is within the acceptable limits and if i want a BT Engineer to be called out i will more than likely be charged for it.

I can understand a slight drop, but from 14 down to 5mibts - Thats a joke.

I have no idea what i can do now to try and get back to what i have been used to for the past 12 months.

Can anyone offer any assistance?

Rgds
Aidi

Edited by deleted (Tue 18-Jun-13 14:15:38)

The same happened to me - from 5/6 mbs now I can only sync at 3072 (2.4mbs real speed) with a 4mbs cap - and BT engineers et al say all is hunky dory.

I believe mine happened when the exchange went to the 21cn or whatever it is called last sept.

Basically, I have given up trying to get it how it was.

Also note the change in our sync speeds is about the same % wise... that is strange.

Nick

Edited by deleted (Tue 18-Jun-13 14:30:38)

If the line is testing OK and there's no crackles/noises when on the phone, and the Margin and Attenuation haven't noticeably changed from how they were before, it's possible 'something' is creating a lot of noise and so lowering the sync floor.

Look for something generating RF noise, either within your own premises or neighbourhood - particularly if it was sudden as it could be somebody has started using a new appliance.

If you are able to monitor and graph your modem stats, it will help in showing if it is constant or intermittent, such as something being switched on/off.

describe your home phone wiring setup

This is where is could be a little difficult to diagnose...

I am in MOD accommodation. The room has a port on the wall - with a BT Openreach box where the filter is currenlty plugged into the test port.

Easiest thing to imagine is the same sort of layout that a Travelodge would likely have.

The whole of the floor (16 rooms in total) all have the same and feed back to a central switch - from there it goes to the BT Exchange.

The other comment made about something having been turned on causing interference is a good possibility, however trying to identify what that could be would be a needle in a haystack.

Rgds
Aidi

so someone else might have had ADSL hooked up in the same cable bundle, or worse. Difficult.

You didn't say if the voice side of things was silent & crackle free, or if testing it with nothing but the router plugged in made a difference.

I would say that at least 1/2 of the rooms have and ADSL connection already.

As for the phone line, its as clear as its always been. With just the router connected i still get the same connection speed.

In reply to a post by akwilliams:

I would say that at least 1/2 of the rooms have and ADSL connection already.

Have any seen the same deterioration?

Have a read of this page. The 80% quoted for the FTR may be correct, or it may be 70%. Information sources vary and I think it started at 70% and was at some stage increased.

Once you have your head round that, ask them what the FTR for your line is. But as the others have pointed out, if the cause is new noise at your end you may have a problem with arguments about charging for callout.

That warning is something all ISPs give when discussing engineer callouts. Basically it relates to where the problem is wrt the demarcation point. The demarcation point is the test socket of your master socket, with you responsible if the cause is your side of it, and Openreach if the other side, whatever goes on elsewhere in the building.

By the "test socket", I assume you are talking about the one on the wall at the back as shown here.

Re the noise itself, has anyone around recently installed a Sky box or a plasma TV? New DECT phones?

In reply to a post by akwilliams:

Easiest thing to imagine is the same sort of layout that a Travelodge would likely have.

I'd imagine a hotel as having a Ethernet port in every room and the ADSL connection in the basement with the modem & router. Not a modem in every room as you seem to say. Do you mean it's a BT OR fibre modem or a BT Home Hub (nowt to do with OR) router?

I think the "Openreach box" is a phone socket. He is with Freeola and the line stats are clearly not FTTC.

Ah, yes! So looks like it's a block of self-contained rooms each with their own phone line. Nowt like a Travelodge at all (which only does chargeable WiFi unlike BestWestern I was last in which did free Ethernet).

what i meant was in design. Perhaps i worded it wrong.

Its 16 rooms each with a port to which the occupier is responsible for getting the phone line activated along with ADSL. Once that is done, it feeds back to a central switch and then out to BT.

So in reality, there could be 16 physical lines and ADSL active at any one time - i suspect there would be about 7 or 8 in this instance.

Call it a "socket" and not a "port" and we'd be clearer.

What I find frustrating is the 'usual' replies to the OP when something happens like this.

Like me, NOTHING changed except the sync speed connection.

I went through the filters/cables wires, washing machines, wind powered auotmatons, elephants in a nearby circus etc.

BUT, for some reason, this happens, and all you get from the engineers is 'all ok'.

I am wondering if it is caused but the upgrades to fibre boxes.

Nick

You should be getting a lot faster, but the noise margin is the issue. One possibility is that one of your neighbours has bought a new electronic device that is radiating a lot of noise. Has occupancy of one of the rooms changed recently? Maybe a Plasma TV?

Get Router Stats Lite and run it for 24 hours to record the SNR and sync speed to see if either changes ...

I am very au fait with these kind of wiring set ups, it is no different than any usual block of flats.

I'd be wondering if there was external interference, as someone else on here has asked, do any of your colleagues in nearby rooms have similar issues ?

Thanks for all the replies.

Trying to find out if someone has a new electrical item plugged in, or something in the vicinity is pretty difficult to determine.

I have spoken to my ISP again, and they have requested that i leave the connection which is currently at 5706kbs on the downstream and holding stable for the next 72 hours and see if it takes any hits (they are monitoring it)

I guess what i am wanting to know now, is if this remains stable at 5607kbs, can they/will they attempt to increase the speed for me step by step until it starts to disconnect? Even if i could get upto 10Mbits (which is 4mbits slower than before) i would be happy!

Rgds
Aidi

With an attenuation of 24dB, the Kitz speed calculator suggests a sync speed of 18Mbps+.

That you have a reduced sync speed alongside a "normal" noise margin of 6dB suggests that there is a lot of noise hitting you, as mentioned in plenty of other posts. If this is stable, then it suggests constant noise; if it varies, then you have a very variable source.

Have you tried using something like RouterStats to track the changes to noise margin over time, and the sync speed over time?

DSLstats does a similar job.

Either might also tell you the SNR values for all the different frequencies and/or the bit-loading values, displayed as graphs. With these, you can see if the noise is happening at specific points in the spectrum, or throughout.

Finally, you mention in a couple of posts that the physical connection goes via a "switch". What do you mean exactly?

To me a "switch" is a telephone exchange like BT's, or a private exchange (PABX) for a company. Going back a few years, these would switch at 64Kbps, and would prevent a broadband connection at all.

I'm sure you mean something else, but it would probably wise to find out if anything changed with the "switch" recently too.

In reply to a post by akwilliams:

I guess what i am wanting to know now, is if this remains stable at 5607kbs, can they/will they attempt to increase the speed for me step by step until it starts to disconnect?

The only way that speed can be increased, from the stats in the OP, is to reduce the noise margin further, making it susceptible to disconnections.

BT's 21CN can run at 3dB, but you need a very stable connection for that to stay connected. The amount of noise you obviously now have suggests that it isn't going to stay stable.

But a 3dB gain will buy you perhaps 1-2Mbps, tops.

In reply to a post by Lethe:

What I find frustrating is the 'usual' replies to the OP when something happens like this.

Like me, NOTHING changed except the sync speed connection.

If "NOTHING" changed the sync speed would be the same. So something changed somewhere, the challenge is to find what.

I have downloaded a couple of stat programs - RouterStats and RouterStats Lite.

The lite version works, but only gives SNR and connection, i cant get the full version to run. Ill hunt around and see if i can get it working.

Where i have said "switch" perhaps distribution point would be a better description.

Each room has Socket on the wall which is the BT socket. These in turn feed to a central location (distribution point) in the building and then i assume goto the exchange.

I have monitored my router stats for the past 18 hours and it remains solid on 6.1db SNR and Line Attenuation is steady at 23.5db. This is pretty much what it has been on since its installation. The SNR sometimes fluctuates down to 5db, but i have never seen it disconnect when it does this - and its not that often it moves from 6.1db

the implication is that something has added interference in the 300 kHz - 1 MHz band and that is reducing your available sync speed.

If you're on a military base there might be a few possibilities for comms or radar equipment to do that.

If the wiring is dodgy then another room getting ADSL could impact on you, or someone could have a dodgy power supply or appliance radiating interference nearby.

An AM radio tuned off-station can be used to listen in to the frequency bands for obvious strong interference. Getting your neighbours to run everything off for an hour might help narrow it down.

If you have Router Stats Lite working that will be enough.

Get it to record and plot SNR and Sync speed every 30 seconds for at least 24 hours. SNR will vary by the seconds and during a day you will see an slow rise and fall of maybe up to 3 dB that is normal.

Then, go and talk to your neighbours, and ask them to turn off everything that they have in their room. Log the times for each room and then go and look at the graph were there any re-syncs? or large SNR changes?

There is the possibility that something outside the building is causing the problem too - are there any construction works on your base?

When I say 'nothing' I mean at my end - obviously something changed, but the BT engineer after all the tests said nothing is wrong.

I agree with the OP that as the 'accepted' government stance is that everybody should get at least a 2mb connection, this is now taken as the acceptable bottom line no matter what is wrong with your adsl connection - if you get =>2mb, all is 'OK'.

Nick

An AM radio tuned off-station can be used to listen in to the frequency bands for obvious strong interference.

Further to Phill's comments, if you can find a portable MW radio tune to 612, and listen at this frequency. If being drowned out by noise, it would be well worth hunting around for the noises strongest point. Bear in mind that some electrical equipment can give noise which isn't a source of interference.

The most commonplace noise/interferer would be a Sky box, this is usually quite a deep 'growl' on the radio. Since it is usually connected into a telephone line, it has an easy path to get on to the network.

Does your router provide errors counters, CRC's FEC's and HEC's, if this IS interference, then these counters may show very high numbers of errors. Again, if it IS interference, I suspect you are some way from the source, because if closer, you'd be seeing drops in sync, maybe even no sync at all.

In reply to a post by Lethe:

I agree with the OP that as the 'accepted' government stance is that everybody should get at least a 2mb connection, this is now taken as the acceptable bottom line no matter what is wrong with your adsl connection - if you get =>2mb, all is 'OK'.

BT lines have fault reporting thresholds for ADSL and VDSL services, these are based on early connection rates. Numpties in call centres may not understand, but sync below FTR is a reportable fault.

In reply to a post by yarwell:

In reply to a post by Lethe:

I agree with the OP that as the 'accepted' government stance is that everybody should get at least a 2mb connection, this is now taken as the acceptable bottom line no matter what is wrong with your adsl connection - if you get =>2mb, all is 'OK'.

BT lines have fault reporting thresholds for ADSL and VDSL services, these are based on early connection rates. Numpties in call centres may not understand, but sync below FTR is a reportable fault.

But if you go the the BT speedtest site and do the diagnostics thing:

http://speedtest.btwholesale.com/

this is what I get (remember, I am less than a mile from exchange in a big city):

Download speedachieved during the test was - 2.76 Mbps
 For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
 IP Profile for your line is - 2.71 Mbps

so how come I could get 5/6 mbps 4 years ago on bog standard adsl?

Nick

the acceptable range of speeds is 1.2 Mbps-4 Mbps.

this refers to throughput at your connection speed.

It says nothing about the current sync speed relative to the FTR and you missed the sync speed out of the cut & paste.

Download speedachieved during the test was - 7.13 Mbps
For your connection, the acceptable range of speeds is 0.6 Mbps-7.15 Mbps.
Additional Information:
Your DSL Connection Rate :8.13 Mbps(DOWN-STREAM), 0.45 Mbps(UP-STREAM)
IP Profile for your line is - 7.15 Mbps

In reply to a post by yarwell:

the acceptable range of speeds is 1.2 Mbps-4 Mbps.

this refers to throughput at your connection speed.

It says nothing about the current sync speed relative to the FTR and you missed the sync speed out of the cut & paste.

Download speedachieved during the test was - 7.13 Mbps
For your connection, the acceptable range of speeds is 0.6 Mbps-7.15 Mbps.
Additional Information:
Your DSL Connection Rate :8.13 Mbps(DOWN-STREAM), 0.45 Mbps(UP-STREAM)
IP Profile for your line is - 7.15 Mbps

Phil,

I don't know why you seem to defend why people's adsl connections all of a sudden drop (like the OP's and mine). You see loads of the same thing posted on here, and people get asked to check this, check that, change this, post stats, rewire this, change filters et al. All to no avail.

Something is going on at the other end... not at the user end.

Revisited, here is full page:

1. Best Effort Test: -provides background information.

Download  Speed
2.77 Mbps
 
0 Mbps 4 Mbps
Max Achievable Speed

 Download speedachieved during the test was - 2.77 Mbps
 For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
 IP Profile for your line is - 2.71 Mbps

2. Upstream Test: -provides background information.

Upload Speed
1 Mbps
 
0 Mbps 0.83 Mbps
Max Achievable Speed

Upload speed achieved during the test was - 1Mbps
 Additional Information:
 Upstream Rate IP profile on your line is - 0.83 Mbps


We were unable to identify any performance problem with your service at this time.
It is possible that any problem you are currently, or had previously experienced may have been caused by traffic congestion on the Internet or by the server you were accessing responding slowly.
If you continue to encounter a problem with a specific server, please contact the administrator of that server in the first instance.

Remember, since I first got adsl in 2004? I always had a speed of around 5/6 mbps - always, until something changed (not my end).

Nick

In reply to a post by Lethe:

I don't know why you seem to defend why people's adsl connections all of a sudden drop (like the OP's and mine). You see loads of the same thing posted on here, and people get asked to check this, check that, change this, post stats, rewire this, change filters et al. All to no avail.

Something is going on at the other end... not at the user end.

If he's anything like me, then he's reacting at the apparent stubbornness of your position.

The largest source of subscriber problems with ADSL *is* from within their own homes. That is a plain, simple, unavoidable fact.

Insisting that the problem is NOT your end, without proper justification, is akin to burying your head in the sand. And just because things worked before, and do not work now, is not a sufficiently proper justification.

One reason, therefore, to get people to check, change, post, rewire etc is precisely because it isn't to no avail. It does actually work. Not for everyone, but for enough people.

Another reason is explained by the fact that many apparent faults are inexplicable, intermittent, and hard to trace. Any work done to both isolate the fault, and identify correlation between fault cause and effect all helps here. An Openreach engineer attends for 2 hours, and is highly unlikely to time his visit to coincide with a repeat of an intermittent fault. Analysis work performed without an engineer present can be helpful.

But all of that, and all of the gains from it, require you to be open-minded. It requires you to stop insisting that the fault CANNOT be here just because you feel like insisting.

Every fault is different, every subscriber is different, and every attempt to troubleshoot is therefore different squared.

After all, pavements don't explode do they? They worked yesterday, so how could they just go up in a flash, bang, cloud of smoke today?

If your line was originally at 5M it'll have a fault rate of 3.5, your 2.7 IP profile looks to be possibly below that.

Don't you get the sync speed fed back from the tester like mine ?

Your DSL Connection Rate :8.13 Mbps(DOWN-STREAM), 0.45 Mbps(UP-STREAM)

In reply to a post by akwilliams:

I have no idea what i can do now to try and get back to what i have been used to for the past 12 months.

Ask your ISP for the IP profile data (if it's BT based) for the last 12 months and what the Fault Threshold Rate of the line was set at on commissioning.

Nope. Just stuck on that speed.

[edit]
OK, I see what you mean. My cisco router reports:

d/s u/s
SNR 25.0 6.0
Cap Used 33% 100%
Atten 38.5 20.0
Speed 3072 1164

See the capacity used? Since I got stuck on this sync, nothing changes. I really do think this is waht has happened to the OP... the sync rate gets lowered, nothing is wrong, all is hunky dory.

Nick

Edited by deleted (Wed 19-Jun-13 18:37:26)

Right, got RouterStats working now.

I have it recording - so will post back the logs here later on this evening to give a few hours worth of data, then leave it running all day tomorrow.

Well, here are my stats after running Routerstats for the past 5 hours:

Noise Margin: 6.0 dB
Connection Rate: 5752 Kbps
Line Attenuation: 23.5 dB
Power: 0.0 dBm
Max Rate: 7612 Kbps

SuperFrames: 1034763
SF (CRC) Errors: 2
Reed Solomon: 134518970
RS Corrected: 7660
RS Un-Corrected: 2
HEC: 2
Errored Seconds: 2
Severe ES: 0

Interleave Depth: 64
Bitswaps: 4477




Noise Margin: 12.5 dB
Connection Rate: 440 Kbps
Line Attenuation: 10.6 dB
Power: 12.8 dBm
Max Rate: 656 Kbps

SuperFrames: 4776
SF (CRC) Errors: 0
Reed Solomon: 3978298
RS Corrected: 0
RS Un-Corrected: 0
HEC: 0
Errored Seconds: 0
Severe ES: 0

Interleave Depth: 8
Bitswaps: 271


Total Uptimes (From SF counts):
WAN: 0 days, 04:55:37
LAN: 0 days, 00:00:00




IP address:

I am assuming these are the figures which will give an indication of what might be going on with my line?

Rgds
Aidi

The graphs will be more interesting, especially with the interleave depth at 64.

Attenuation of 23.5/10.6 - the ratio is reasonable.
DS sync speed is very low for that attenuation, but with a 6dB margin you will not get much more. Upstream is OK with plenty of margin left.

It really does sound as though there is a noise issue somewhere. You do need to check with your neighbours, left, right, up and down.

You need to upload the graphs and/or the csv log file to somewhere and give us a link. There are several free sites we can suggest if you don't know any.

The point is we can see the behaviour pattern from those, whereas you have simply posted another snapshot set of stats, which doesn't help us help you at all.

yours has a 25 dB downstream SNR though, which is in no way the same scenario as the OP.

Yours looks like a capped / banded speed. His doesn't. Your DS attenuation is the same as mine.

In reply to a post by yarwell:

Don't you get the sync speed fed back from the tester like mine ?

Your DSL Connection Rate :8.13 Mbps(DOWN-STREAM), 0.45 Mbps(UP-STREAM)

No, you only get that on 20CN.

For the up time, the amount of FEC R/S errors looks stupidly high, that with the low sync for attenuation.

Still looks likely for REIN in my book.

How can tests to investigate a greatly reduced sync rate even suggest that traffic congestion or slow server response could be responsible?

Sorry, I don't know what you mean?

Nick

It's a simple question. How can slow thoughput influence your sync speed?

?
I don't see where he suggested it does, at least not in the post that grahammm replied to.

In reply to a post by RobertoS:

?
I don't see where he suggested it does, at least not in the post that grahammm replied to.

Yes, exactly - that is what I don't understand? And I never have anywhere anyway.

Nick

It probably stems from this

In reply to a post by Lethe:

Like me, NOTHING changed except the sync speed connection.

Hey all,

Well the router has been up a while now, and as promised here is a few screenshots from Routerstats:

[IMG]http://i1358.photobucket.com/albums/q773/aidiwilliam...[/IMG]"]

[IMG]http://i1358.photobucket.com/albums/q773/aidiwilliam...[/IMG]

[IMG]http://i1358.photobucket.com/albums/q773/aidiwilliam...[/IMG]

[IMG]http://i1358.photobucket.com/albums/q773/aidiwilliam...[/IMG]

[IMG]http://i1358.photobucket.com/albums/q773/aidiwilliam...[/IMG]

Other than being stable, on its last reboot, the sync speed was t 5706Mbits, its slowly starting to creep up. Sync is now 6062Mbts

Hope you guys can make something of this before i go back to my ISP to see what they can do next.

Rgds
Aidi

Interference looks constant

It's not really a fault as such.
Your sync is a best effort given everything around you.
A neighbours sky box may have become faulty and caused this. Narrowing that down is very difficult for an ISP.

All the ISP is seeing is that at the lower sync the line is stable, not dropping out and is passing the tests.

It works fine - just much slower than before. From the ISPs viewpoint it's not faulty as its working and passing the tests.

It's annoying but the best diagnosis is to see if neighbours are affected too.

Have you tried the obvious - new adsl filters on everything?

Sounds daft but this can be quite significant

Everything...

Cables, filters, router, different PC. Took out all the originals and replaced with spares which i had. Exactly the same results i'm afraid.

Thanks for taking a look at the stats.

Since the initial drop, the sync speed has crept up a small amount. If the problem which caused the drop in sync in the first place was only temporary, am i likely to see the sync speed increase over time?

I noticed that it has gone from 5706 to 6062. Would i be right in saying that the IP Profile will start to increase automatically over time if it sees a stable line?

In reply to a post by akwilliams:

Since the initial drop, the sync speed has crept up a small amount. If the problem which caused the drop in sync in the first place was only temporary, am i likely to see the sync speed increase over time?

Sync speed is negotiated at sync time, if the interference isn't there at the time it'll sync faster. If it comes along later it may trigger a resync to a lower speed.

It won't "creep up" but you may see step changes if the SNR margin target adjusts based on stability.

Your graphs need to cover a longer time period - can you set it up to run for 24 hours with 30 second samples. An 80 minute snapshot is not really sufficient.

You can create a single graph with SNR and Sync speed together.

It was in last paragraph of the report

We were unable to identify any performance problem with your service at this time.
It is possible that any problem you are currently, or had previously experienced may have been caused by traffic congestion on the Internet or by the server you were accessing responding slowly.
If you continue to encounter a problem with a specific server, please contact the administrator of that server in the first instance.

Well, For whatever reason i decided to reset my router this afternoon...

When it re-sync'd this is what i was met with:

ADSL Link Downstream Upstream
Connection Speed 13707 kbps 959 kbps
Line Attenuation 24.0 db 10.7 db
Noise Margin 6.3 db 6.6 db

Downloads are pretty slow at the moment, but its normally like this late afternoon. Ill test it later when its quieter to see if its working at full speed.

I have done nothing whatsoever to get the increase in speed! Can only assume that it was something that BT has done, or as suggested something electrical was causing the problem somewhere in the vicinity.

Hope i am not counting my chickens too soon!

Rgds
Aidi

Well, that was short lived. Back down to 5106k.