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Standard User arnoldjrimmer
(newbie) Wed 21-Sep-16 09:23:10
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Mysterious ADSL throttling issue


[link to this post]
 
Hi all. I'd be really grateful for any thoughts anyone has as to the cause of a strange problem I have with my Talk Talk ADSL service:

When things are working well, I get download speeds of around 9 Mbps, and upload speeds of around 1 Mbps.

After getting up one morning about 2 months back, I found the broadband seemed extremely slow (both via Wifi and ethernet); even the Google home page was taking half a minute or more to appear: it was virtually unusable.

I ran a speed test using an app on my phone and saw that download speeds were only around 0.2 Mbps. Strangely, upload speeds were unaltered, still at around 1 Mbps.

Restarting the router initially did not help, until about the 3rd or 4th try, when suddenly my normal 9 Mbps download rate was back.

This has been continuing ever since. The upload speed always seems fine, but the download speed will regularly (about once a day) drop to less than 0.5 Mbps. This occurs most often when the router has been off for a bit and is then turned back on, or if the router has not been used much (eg. after leaving it on overnight) and then we try to use it. However, there have even been a couple of occasions where it did suddenly drop in the middle of a normal day, though that seems less common.

On some occasions I've had to restart the router 5 or 6 times, and even wait a few hours before trying again, before normal download rates are restored.

I have tried with 3 different routers and the problem happens with all of them, so this does not seem like it can be due to a router fault.

Does it sound like an ISP/BT issue, perhaps to do with their throttling software not working properly?

Would be really grateful for any ideas!
Standard User micksharpe
(legend) Wed 21-Sep-16 09:39:23
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Re: Mysterious ADSL throttling issue


[re: arnoldjrimmer] [link to this post]
 
It does rather sound like a line issue. What are your router stats (connection speed / line attenuation / noise margin)?
Standard User arnoldjrimmer
(newbie) Wed 21-Sep-16 09:53:12
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Re: Mysterious ADSL throttling issue


[re: micksharpe] [link to this post]
 
Hi Mick, thanks for your reply. Here are the current stats from the router. At the moment it is "working" ie. I am getting my normal 9Mbps'ish download speeds - not sure if the stats are still useful, or you'd need to see them when the bandwidth is misbehaving?

Mode: ADSL2 PLUS
Type: ANNEX_A
Status: Showtime

Rate (Kbps): 11390 kbps (Downstream) 1020 kbps (Upstream)

SNR Margin (dB): 11.0 (Downstream) 13.9 (Upstream)
Attenuation (dB): 27.9 (Downstream) 14.4 (Upstream)
Output Power (dBm): 0.0 (Downstream) 12.7 (Upstream)

Super Frames: 512714 (Downstream) 512714 (Upstream)
RS Correctable Errors: 4679 (Downstream) 0 (Upstream)
RS Uncorrectable Errors: 24 (Downstream) 65506 (Upstream)

HEC Errors: 183 (Downstream) 0 (Upstream)
Total Cells: 55124 (Downstream) 100682 (Upstream)
Data Cells: 15456359 (Downstream) 1345866 (Upstream)
Bit Errors: 0 (Downstream) 0 (Upstream)


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Standard User micksharpe
(legend) Wed 21-Sep-16 10:06:09
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Re: Mysterious ADSL throttling issue


[re: arnoldjrimmer] [link to this post]
 
Your SNR margins are rather high considering your line attenuation although your speed is OK right now. This is probably caused by periods of instability. You need to check these figures again when your connection goes slow.
Standard User micksharpe
(legend) Wed 21-Sep-16 10:43:10
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Re: Mysterious ADSL throttling issue


[re: arnoldjrimmer] [link to this post]
 
You should also do a quiet line test. You will need to disconnect your modem/router and connect a telephone handset directly to the test port in your master socket.
Standard User eckiedoo
(fountain of knowledge) Wed 21-Sep-16 13:07:32
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Re: Mysterious ADSL throttling issue


[re: micksharpe] [link to this post]
 
As well as doing the QLT from the Test Socket as suggested by Mick, you should also try it from an in-house socket, with all the normal BB and other phone equipment connected - as the cause may be within your own equipment.

Especially on those early tests, wait until you have heard the "Quiet Line Test" Announcement at least 5 times, roughly one minute.

I also do the QLT about once per month, even when I have no reason to suspect Line Problems.
Standard User arnoldjrimmer
(newbie) Wed 21-Sep-16 13:21:16
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Re: Mysterious ADSL throttling issue


[re: micksharpe] [link to this post]
 
Hi Mick.

Quiet Line Test

This is hard to do properly because my master socket does not have a test socket in it, and with Talk Talk the 17070 number does not a quiet line test option. I have plugged my phone directly into the main socket, dialed a conference call that had no-one on it, and listened: the line is pretty clear: no crackles or scratching noise; there is a quiet background hum, that is all.

Router Stats

By restarting my router a few times I managed to re-create the "slow download speeds" problem this lunch time. Whilst like this, my phone app was showing download speeds of around 0.15 Mbps; I couldn't even run a speed test on my ethernet-connected laptop since the speed check website was just too slow.

Below are the router stats during this period - not sure if they are enlightening or not!

Mode: ADSL2 PLUS
Type: ANNEX_A
Status: Showtime

Rate (Kbps): 11237 kbps (Downstream) 1020 kbps (Upstream)

SNR Margin (dB): 12.1 (Downstream) 13.7 (Upstream)
Attenuation (dB): 28.6 (Downstream) 14.4 (Upstream)
Output Power (dBm): 0.0 (Downstream) 12.6 (Upstream)

Super Frames: 17488 (Downstream) 17488 (Upstream)
RS Correctable Errors: 87 (Downstream) 0 (Upstream)
RS Uncorrectable Errors: 0 (Downstream) 0 (Upstream)


HEC Errors: 0 (Downstream) 0 (Upstream)
Total Cells: 60930 (Downstream) 38400 (Upstream)
Data Cells: 126466 (Downstream) 103936 (Upstream)
Bit Errors: 0 (Downstream) 0 (Upstream)
Administrator MrSaffron
(staff) Wed 21-Sep-16 13:24:16
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Re: Mysterious ADSL throttling issue


[re: arnoldjrimmer] [link to this post]
 
Modem is connecting fine still, ie. data rate showing 11 Mbps and no surge of errors.

So implication maybe that you are hopping between gateways with the provider and sometimes finding a very bad one.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User RobertoS
(elder) Wed 21-Sep-16 13:36:09
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Re: Mysterious ADSL throttling issue


[re: MrSaffron] [link to this post]
 
+1

Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. Sync 57825/13835kbps @ 600m. - BQM
Standard User arnoldjrimmer
(newbie) Wed 21-Sep-16 14:01:45
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Re: Mysterious ADSL throttling issue


[re: MrSaffron] [link to this post]
 
Thanks for your thoughts!

If I phone my ISP (Talk Talk) and report this, is it something that they should be able to fix?

As a last resort, would swapping to a different ISP, or upgrading from ADSL to Fibre broadband solve this kind of problem, if it is gateway-related?
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