Sudden change in achievable download speeds

[#1]

Hello,

Can anyone make any useful suggestions based on the below: 

Plusnet website suggests: 

* Estimated line speed:80Mb (This may vary between 72Mb and 80Mb) - Checked on 2017-10-24 09:36:35

* Current line speed:65 Mb

Modem tells me: 

Status: UP
Line State: showtime_tc_sync [0x801]
Line Mode: G.993.2 (VDSL2)
Annex: B
Profile: 17a
Data Rate: 68.756 Mb/s / 20.000 Mb/s
Max. Attainable Data Rate (ATTNDR): 79.385 Mb/s / 22.082 Mb/s
Latency: 8.0 ms / 0.0 ms
Line Attenuation (LATN): 16.3 dB / 16.9 dB
Signal Attenuation (SATN): 16.3 dB / 16.7 dB
Noise Margin (SNR): 6 dB / 6.2 dB
Aggregate Transmit Power(ACTATP): 6 dB / 6.2 dB
Forward Error Correction Seconds (FECS): 103 / 88949
Errored seconds (ES): 0 / 2729
Severely Errored Seconds (SES): 0 / 39
Loss of Signal Seconds (LOSS): 0 / 202
Unavailable Seconds (UAS): 35 / 35
Header Error Code Errors (HEC): 0 / 0
Non Pre-emtive CRC errors (CRC_P): 0 / 0
Pre-emtive CRC errors (CRCP_P): 0 / 0
Line Uptime: 22m 20s
ATU-C System Vendor ID: Infineon 178.6
Power Management Mode: L0 - Synchronized

BT wholesale speedtest results range from 60Mbps to 35Mbps when run multiple times

My own periodic tests show that until about 11 days ago I was reliably getting the high 60s down, and about 20 up. This then suddenly changed to 50s down (up still steady at around 20) :

http://bbarker.duckdns.org/speed/index.php?interval=720

I have a ticket open, but nobody seems quite sure what is going on...suggestions welcome 🙂  There seems to be a massive gap between "data rate" and "maximum data rate" - but I'm not sure on what metrics the latter is based...

[#2]

Another sustained speed drop to ~45Mbps down, whilst other router stats remain unchanged...

I managed to speak with phone support today, who were very polite, but were only able to suggest sending another OpenReach technician...

The first one found nothing wrong, and the line stats seem stable....not sure why the second one will do any better....

Hmmm......

[#3]

Could be similar to a number of other capacity problems under investigation by PN and BT QA.  I'll tag @Gandalf to take a look at your case.

Superuser citation

This topic has been cited by one of the Superusers; the purpose of which is to provide a note for information which might help to focus continued discussion (but might not result in a staff response).

[#4]

Welcome to the community forums @dbrb22

I've flagged this with the relevant people to further investigate. We'll let you know when we've got more info.

[#5]

Thanks. Fingers crossed....
The last open reach technician seemed to think the line was ok, and the changes (two now) seem quite sudden when they occur....

Is there still value in the planned visit next week? I have to be at home, which is tricky, so if the issue lies elsewhere I may try to cancel it....

[#6]

At this stage, if another engineer visit will cause inconvenience to you I'm happy to cancel it?

Once we've investigated this*, if the problem still exists we can always rebook it in.

*I've included your account as part of a bigger picture we're looking at with regards to VLAN issues.

We should hopefully have more info next week.

[#7]

Thanks - yes, can we cancel for now?

Cheers,

Ben

[#8]

Done. No problems Ben. I'll pick this back up Tuesday, as that'd be the earliest we'd have some form of update.

[#9]

Interesting - had a call from OpenReach today, very helpful guy. I'm not syncing at 76Mbps again - though my achievable download speeds are yet to shift from a fairly stable ~45....

[#10]

It looks like we changed the speed profile on your account last night which would've likely been limiting your throughput.

What are your speeds like since then?

[#11]

Good and bad 🙂

My sync speed has remained stable at a respectable ~78Mbps down

My achievable speeds from scheduled test runs vary from ~72 down during the day to ~40 down in the evening

Interestingly, when this happens (see link in original post) it isn't a gradual tail off, but a sudden change...

Capacity issues? 

[#12]

@MatthewWheeler  Can you pick this case up as part of @Gandalf ongoing investigations please.

[#13]

Not sure if someone has done something... but things have, for the moment, become a lot more stable:

http://bbarker.duckdns.org/speed/index.php?interval=168