S/N goes up and download speed goes down....again!

[#1]

After requesting a 'retrain' some weeks back after my speed dropped to 23Mbs with a high s/n ratio of around 12dB my download connection successfully returned to the 29Mbs I started with when I switched to fibre and stayed at this speed for some weeks.
Now because of another bout of random line drops (less than once a day) my profile seems to have reverted back to setting the s/n to around 12dB again, meaning the speed has been dropped back to 23Mbs. Can you initiate another 'retrain' and maybe change my profile to stop this happening again.
It's odd how the speed always drops to just above my minimum guaranteed speed, almost like it is deliberate?

Ian

[#2]

Hi @chroma, sorry to hear you're having broadband issues.

I've had a check of the connection and there definitely seems to be something out of place somewhere as we can see the disconnections from this end. Your speeds are also below the estimated currently, although our tests aren't picking up exactly what's causing the issue so we will have to do some troubleshooting to start ruling things out.

I'd recommend starting with basic checks here

And if that doesn't help the next thing would be to rule your internal wiring out by plugging the connection into your test socket which is under the faceplate of your master socket and seeing if the drops stop. This rules out internal wiring, face plates and extension sockets as being the cause. How to locate the test socket and set your connection into it can be found here

If the problem still persists from here we will go down the route of raising a fault from here and let us know once you've done the checks and raised the fault so we can progress it for you.

[#3]

Hi Faris,

I've done all the usual tests that I can do. It was only a few weeks ago that I had two engineer visits which ruled out any connection problems at my end. It turned out to be a bad connection at the pole outside and fixing it did improve it for some weeks before something happened to knock the speed down again necessitating a retrain to optimise the speed versus s/n. Once again it was all fine for a few weeks until now.  Wherever the problem is it isn't my end that's for sure.

Regards, Ian.

[#4]

All updated for you here @chroma2000.

Thanks.

[#5]

My connection has held up for nearly 3 days now. Unfortunately it is still stuck at 23Mbs and 11.5db s/n. Why can't my profile be set to a target s/n of 6dB so that when it does drop out it will recover back to around 29Mbs?

[#6]

I was on  44910Kbps /  6.1dB just over a month ago,. Now on 33478Kbps / 12.1dB

PN say there is nothing wrong with my line

Obviously the SNR is affected by more than disconnects.

[#7]

The cynic in me says it's a way of reducing our download speeds to save them bandwidth.

I'm quite willing to accept the occasional disconnect for a higher connection rate. Perhaps we should decide which is most important for our usage.

When I was on ADSL the exchange always seemed to balance speed vs s/n to optimise the connection. Now it seems once the speed has gone down it stays down unless a 'retrain' is initiated. This seems to be a very simple thing to do so I don't know why the line can't do it automatically from time to time.

[#8]

Hi @chroma2000

Unfortunately, we can't pin the SNR margin on fibre connections - the software will reduce the speed as it feels is needed and in principle elevate it again when the line is stable.

I've just checked your sync speed and you're still in sync at around 23mb/s - if this doesn't increase naturally over the next few days I would strongly recommend progressing with the engineer - I can see that you're provided your availability already, please just drop us a message here when you'd like to go ahead with this.

Best wishes

Dave

[#9]

Hi Dave,

Experience has shown that whilst the software is good at reducing the speed it doesn't seem to be successful in bringing it up again.

Unless you can manually initiate a 'retrain', as was done last time, it will be necessary to go the 'engineer' route.

Regards, Ian.

[#10]

And an engineer means half a day (or a full day) off work because as Ian has said the kit seems more than happy to reduce speed and increase SNR but seems pretty loath to, or incapable of, increasing speed and SNR in any reasonable time frame.

It's 2019 - It really should not mean customers taking time off work for someone to reset the line to force a retrain. 

[#11]

A few disconnects at less than 1 a day was enough to cut the speed, but now despite being up for nearly 4 days no sign of any reversal. I wonder how many customers end up anywhere near the top of the predicted connection speed, I would guess that most end up close to the bottom which is very convenient from plusnet's point of view!

[#12]

Thanks for getting back to us @chroma2000 I'm sorry to see you feel that way.

Unfortunately that there's nothing we can do to manually cause your fibre line to retrain/re-sync apart from perform a line test but this generally doesn't drop sync unless you're on standard broadband.

If it was possible we'd happily do it but I'm afraid you're asking something of us we can't do. It looks like previously what we did was re-order your fibre service to reset the line, which isn't the correct process or what we should've done because it can cause further issues with other aspects including the billing.

We have a process with our suppliers to reset a line if it is banded, however I can see your sync rate at 23.8mbps and your line banded at 30mbps so a reset wouldn't benefit you and something we'd not be able to request based on this.

There does certainly appear to be underlying problem somewhere causing your sync speeds to be restricted continually and as your speeds are below the expectations/speed estimates of your line, this needs an engineering investigation. 

With this in mind, I've booked an engineer visit for this Friday between 1pm and 6pm.

Can you let us know how you get on? Thank you.

[#13]

The openreach engineer could find no fault with the line or reason why the speed was being capped at 23Mbs.

After resetting the line the speed has now risen to 35Mbs with a s/n ratio of about 6dB as shown below and at the moment is stable.

There remains however the problem of how this speed restriction will be dealt with when it happens again. It should not be necessary for an engineer to have to visit each time just to reset the line. Once whatever has caused the restriction has passed there needs to be an automatic mechanism in the system to re-optimise the line.

I wonder how many other customers have been restricted in this way but haven't actually noticed it?

DSL uptime:0 days, 17:57:33
Data rate:7611 / 35755
Maximum data rate:7610 / 36370

Noise margin:6.0 / 6.1

Line attenuation:28.9 / 24.5
Signal attenuation:29.0 / 22.1

[#14]

Hi Chroma 2000 I have the exact same fault "its like bashing your head against a wall". my stats are

Upstream line rate (kbit/s):

7267

Downstream line rate (kbit/s):

22399

Upstream noise safety coefficient (dB):

6.2

Downstream noise safety coefficient (dB):

12.3 

These snr rates show if the ip profile was reset i.e the download would drop from 12.3 back to 6.3 and the download speed would rise back to 32Mbs.

Please read my heading  Slow Broadband "here we go again"

[#15]

SORRY WRONG HEADING            Unstable Fibre Speed "Here we go again"