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Why is my maximum achievable speed now only 4 Mbps?

Lynnpin
Grafter
Posts: 85
Thanks: 2
Registered: 31-07-2012

Why is my maximum achievable speed now only 4 Mbps?

Is there any reason why my max achievable speed is now so low?  My exchange was upgraded about 8 months ago and I would have expected higher maximum speeds not lower.  Below is a read out from the BT performance test so I'm at the top end of the scale and yet I'm sure it used to be around 8 Mbps max but then I was only getting around 2 mbps.  So although it is faster, it is actually slower if you see what I mean!  Is there some kind of cap on my potential line speed?
Max Achievable Speed: 4 Mbps
Download speed achieved during the test was - 3.67 Mbps
For your connection, the acceptable range of speeds is 1.2 Mbps-4 Mbps.
IP Profile for your line is - 3.8 Mbps
Upload speed achieved during the test was - 0.75Mbps
Additional Information:
Upstream Rate IP profile on your line is - 0.83 Mbps
13 REPLIES
Community Veteran
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Registered: 10-06-2010

Re: Why is my maximum achievable speed now only 4 Mbps?

That acceptable range of speeds doesn't mean anything, it may be more to do with the fact that beyond your exchange, bandwidth is shared between many users, and for that reason it's not guaranteed everyone will be able to max out their line 100% of the time.
We need the line stats from your router to see if the speed you're getting is the best possible or not. For longer lines, ADSL2+ may provide little or no increase in speed, and you probably won't even have been switched to ADSL2+ anyway. So your exchange having been upgraded won't necessarily increase your speed.
Lynnpin
Grafter
Posts: 85
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Registered: 31-07-2012

Re: Why is my maximum achievable speed now only 4 Mbps?

Is that the DSL connection link info you mean?  If so, this is it below but if not how do I find it?
Uptime: 26 days, 18:08:20
DSL Type: G.992.3 annex A
Maximum Bandwidth (Up/Down) [kbps/kbps]: 984 / 3,492
Bandwidth (Up/Down) [kbps/kbps]: 939 / 4,312
Data Transferred (Sent/Received) [MB/GB]: 480.07 / 7.10
Output Power (Up/Down) [dBm]: 12.5 / 18.5
Line Attenuation (Up/Down) [dB]: 27.0 / 47.0
SN Margin (Up/Down) [dB]: 7.0 / 2.5
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 327,677 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 857,225 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 4,161 / 298,671
HEC Errors (Up/Down): 5,236 / 1,062,166
Community Veteran
Posts: 5,172
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Registered: 10-06-2010

Re: Why is my maximum achievable speed now only 4 Mbps?

Yes, that's the right information. You are on ADSL2, 4312 down for a 47db isn't great, according to the Kitz max speed calculator about 5-6Mb would be the best possible. Some of the error counts look quite high, but then those stats are for almost 27 days or could just be reported wrong (like the 327,677 Loss of Signal errors?) .
Lynnpin
Grafter
Posts: 85
Thanks: 2
Registered: 31-07-2012

Re: Why is my maximum achievable speed now only 4 Mbps?

I must admit these stats mean nothing to me so I don't know if they are good, bag or ugly.  I did have a lot of problems the year before last with constant disconnections (see http://community.plus.net/forum/index.php/topic,106632.msg924113.html#msg924113 for older DSL connection log) and just getting a reliable and constant service was more important then.  It seems to have been more stable recently but I did find the following  BT performance test done on 12 February 2012 last year when they reckoned my max speed was 7.15 Mbps.
Max Achievable Speed: 7.15 Mbps
Download speed achieved during the test was - 2.9 Mbps
For your connection, the acceptable range of speeds is 600 Kbps-7.15 Mbps.
IP Profile for your line is - 3.5 Mbps
Your DSL Connection Rate: 4.42 Mbps (downstream)  448 Kbps (upstream)
Community Veteran
Posts: 5,172
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Registered: 10-06-2010

Re: Why is my maximum achievable speed now only 4 Mbps?

That different "Max Achievable Speed" and range of speeds "600 Kbps-7.15 Mbps" was just due to the older ADSL1 20CN system from before your exchange was upgraded to 21CN and ADSL2+.
The "1.2 Mbps-4 Mbps" is determined by your line speed. It does not control or restrict your line speed to a max of 4 Mbps. If you managed to improve your setup or wiring and got a higher speed, the BT speedtester would show a higher range of speeds.
Lynnpin
Grafter
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Registered: 31-07-2012

Re: Why is my maximum achievable speed now only 4 Mbps?

So is it my poor set up that is causing it? I did buy a better quality cable as mentioned in the post above but I never got around to changing it as I was so pleased that the thing wasn't switching on and off all the time.  Maybe I should try that.
Superuser
Superuser
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Registered: 06-04-2007

Re: Why is my maximum achievable speed now only 4 Mbps?

Internal wiring could be the source of the problem, but it might be external. Is your router plugged into the master socket or an extension?
If your master socket is the NTE5 type (see the wiring link provided by ejs) plugging your router via a filter into the test socket shown there should eliminate internal wiring effects. If you can do that posting the router stats (DSL Connection information) like those you posted earlier would help to show if the problem is internal or external. (Speedtests won't react quickly enough.)
When moving the router it's best to use the router's web interface to disconnect from Plusnet first; this should stop the DLM at the exchange thinking the disconnection might be a fault.
David
Lynnpin
Grafter
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Registered: 31-07-2012

Re: Why is my maximum achievable speed now only 4 Mbps?

No, I don't have an NTE5 socket just the old style circa 1976 but the router is plugged into the master socket although it is on a long cable meandering upstairs and across the landing.  Maybe the better quality cable I bought would make a difference.
Superuser
Superuser
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Re: Why is my maximum achievable speed now only 4 Mbps?

Having the router on a long telephone cable is generally bad news and could be the source of the problem. It's definitely worth trying the alternative cable that you purchased. Having the router downstairs would be better - but other questions need then to be asked.
David
Lynnpin
Grafter
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Registered: 31-07-2012

Re: Why is my maximum achievable speed now only 4 Mbps?

Yes, I realise it's not ideal having a long cable but in my previous thread mentioned above I explained it was due to a problem with sockets.
Community Veteran
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Re: Why is my maximum achievable speed now only 4 Mbps?

Is your extension cable a flat type?  These are OK for telephone but definitely not so good for broadband.  Any ADSL cable should be 'twisted pair' which helps to avoid interference.
Call me 'w23'
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Lynnpin
Grafter
Posts: 85
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Registered: 31-07-2012

Re: Why is my maximum achievable speed now only 4 Mbps?

Quote from: w23
Is your extension cable a flat type? 

Yes it is but the new one I bought (suggested by Anotherone from ADSLnation in the other thread mentioned above) is a twisted pair so I really must change them over.
Superuser
Superuser
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Re: Why is my maximum achievable speed now only 4 Mbps?

It's definitely worth trying the new cable and posting the new router stats.
David