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Apparent Throttling of Speed on Plusnet Pro

baker2009
Dabbler
Posts: 13
Registered: ‎12-04-2012

Apparent Throttling of Speed on Plusnet Pro

Hi.
I've been a customer your Plusnet Pro service for nearly 3 years now.
I can't remember a time when I have had a run or more than a month with no speed issues. I have posted countless questions, and never managed to get to the bottom of the problem - so thought the experts here might be able to help me.
Currently on Bourton-on-the-Water exchange (upgraded to BT21CN services in Feb 2012) with a line sync/profile set at about 17000kbps. Sounds great, often works brilliantly, but in realitly....every few days I get a connection that starts stuttering....(I often use it to watch Netflix/Video streaming). Speed tests show a suspicious top speed steady at around 1.0MBps exactly and remain so for some time.  As I write, this just happened, and now (nearly 2:00am) things are back up to 15Mbps (the usual fast speed).  I live very close to the exchange and in a new (less than 3 year old) property with brand new wiring.
Customer services always point out that I am not being 'throttled'/'usage capped' by Plusnet (despite one accidental case a few months back, which they refunded me for) yet I have excellent line latency/ping speeds - between 10 & 40 ms avg, with 1-2ms jitter. All things point to occasional throttling, which if it's not plusnet, would have to be at the BT Exchange? A bit of Google Searching has thrown up several refernces to 'Secret Throttling' by BT, but no help on how to prevent it.
The bottom line for me, with the upmost respect to Plusnet (v good customer service) is that with the advent of multimedia streaming, high quality- line-speed, minimal traffic-managed b/band is essential to me.  I am paying for the Extra (60Gb download limit, with no planned cap on exceeding this either) and the Pro add-on, so why do does my line keep falling over?
Thanks for any help you can provide. Undecided
(Plusnet Extra, Pro Add-on, No Caps, Netgear DGN3500 latest Firmware V1.1.00.33_1.00.33, Tried plugged into main socket with no extensiosn connected, and wired via ethernet cable to laptop/apple TV)
30 REPLIES
Blim
Grafter
Posts: 462
Registered: ‎06-03-2012

Re: Apparent Throttling of Speed on Plusnet Pro

out of interest is that your ip profile changing or does that stay the same while your download speed test is reporting lower?
just wondering if your line sync is changing.

blim

plusnet customer.
jojopillo
Grafter
Posts: 9,786
Registered: ‎16-06-2010

Re: Apparent Throttling of Speed on Plusnet Pro

Hi baker2009
I notice that were a lot of disconnections last night (see graph). Are you aware of what caused them?
Jojo Smiley
baker2009
Dabbler
Posts: 13
Registered: ‎12-04-2012

Re: Apparent Throttling of Speed on Plusnet Pro

In answer to both questions...Yes, my IP profile/sync speed remains fairly steady at around 15000 to 17000 Kbps, but downloads all appear throttled intermittently. When this happens it has been lasting for several hours at a time, in most cases showing a steady /exact 1Mbps download rate on speed test.net. All the disconnects you see are me having to reboot the router to try and remove the throttle. Sometimes it works (tonight it did, after slowing to around 0.8Mbps which was not enough to watch a netflix TV episode in HD. After reboot, back to 14MBps download rate as measured by speedtester.net and was then able to watch 2hrs of HDcontent flawlessly, and login to send this reply.
Here's the snag: everytime it happens, it's often not fast enough to even register an official result at BT Speedtester! Often it just says Error occurred! Then once forced to reboot/wait hours/days, it's upto 14Mpbs and funny old thing, BT speedtester results look great!
I'm utterly convinced (as evidenced by my usual v fast performance, low ping, low jitter, good line quality) that BT or elsewhere are throttling back my line either by mistake/exchange software error or other reason that I know not how to track.
Any advice? I ended up replacing my router for the same reasons 2 yrs ago, and now realise that perhaps it was a wasted effort.
I see u had the exact same issue here Blim > http://community.plus.net/forum/index.php/topic,103927.0.html
That's no router/filter problem, or a coincidence is it?!
Community Veteran
Posts: 26,722
Thanks: 936
Fixes: 10
Registered: ‎10-04-2007

Re: Apparent Throttling of Speed on Plusnet Pro

Unless I've missed it I don't think you've said is you are using a wired or wireless connection to the router.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
Community Veteran
Posts: 6,319
Thanks: 86
Fixes: 3
Registered: ‎08-01-2008

Re: Apparent Throttling of Speed on Plusnet Pro

Quote
(Plusnet Extra, Pro Add-on, No Caps, Netgear DGN3500 latest Firmware V1.1.00.33_1.00.33, Tried plugged into main socket with no extensiosn connected, and wired via ethernet cable to laptop/apple TV)
Call me 'w23'
At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.
Opinions expressed in forum posts are those of the poster, others may have different views.
baker2009
Dabbler
Posts: 13
Registered: ‎12-04-2012

Re: Apparent Throttling of Speed on Plusnet Pro

OK, here's one thought - what is the recommended MTU size value to set on my router for plusnet?
Someone with the same issue here > http://usergroup.plus.net/forum/index.php?topic=7160.0
Here are my current settings: -
Router Status

Account Name 
Firmware Version V1.1.00.33_1.00.33 

ADSL Port 
MAC Address 00:26:F2:3D:9E:29
IP Address 91.125.161.104
Network Type PPPoA
IP Subnet Mask 255.255.255.255
Gateway IP Address 195.166.130.48
Domain Name Server 212.159.6.9
212.159.6.10

LAN Port
MAC Address 00:26:F2:3D:9E:28
IP Address 192.168.0.1
DHCP On
IP Subnet Mask 255.255.255.0

Modem 
ADSL Firmware Version 4.5.0.12.0.1
Modem Status Connected
DownStream Connection Speed 14909 kbps
UpStream Connection Speed 916 kbps
VPI 0
VCI 38
MTU Size (in bytes) 1492

Netgear advice on MTU :-
MTU Size
The normal MTU (Maximum Transmit Unit) value for most Ethernet networks is 1500 Bytes, 1492 Bytes for PPPoE connections, 1436 for PPTP, or 1428 for L2TP connections. For some ISPs you may need to reduce the MTU. But this is rarely required, and should not be done unless you are sure it is necessary for your ISP connection.
Plusnet recommend 1400 for one type of router (d_lInk) and also offer this advice.... http://community.plus.net/library/settings/guide-to-rwin-mtu/
Might have a go....any advice?
jojopillo
Grafter
Posts: 9,786
Registered: ‎16-06-2010

Re: Apparent Throttling of Speed on Plusnet Pro

Hi baker2009,
What router is it you are using? Are VPI &VCI set to 0 & 38 and on VC based?
I can see from testing that there is some issue afoot. You should get an update from the faults team later. The problem with Blim was his SNR was dropping causing poor performance. This doesn't look like the same issue to me.
Jojo Smiley
baker2009
Dabbler
Posts: 13
Registered: ‎12-04-2012

Re: Apparent Throttling of Speed on Plusnet Pro

Hi Jojo,
See above, and also:-
System Up Time 12:54:46
ADSL Link                  Downstream            Upstream
Connection Speed    14909 kbps              916 kbps
Line Attenuation        23.1 db                    14.6 db
Noise Margin              9.4 db                      6.3 db
Of interest i remember seeing the downstream at 6.3db the other day? Shall I power on/off again and have another look?

Community Veteran
Posts: 26,722
Thanks: 936
Fixes: 10
Registered: ‎10-04-2007

Re: Apparent Throttling of Speed on Plusnet Pro

Re MTU.
The critical thing is that the MTU on your PC must not be larger than on the router, same is ideal. If the router MTU is larger than the PC I've never seen proof that it has an adverse effect.
Based on that I always advise setting the router to 1500 and forget it!
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
baker2009
Dabbler
Posts: 13
Registered: ‎12-04-2012

Re: Apparent Throttling of Speed on Plusnet Pro

Thanks for the advice.
I've heard similar things before. Did the test here, and looks good at mo with 1492, Jojo any thoughts? 1492 or 1500?
http://www.dslreports.com/tweakr/block:4b04824?service=dsl&speed=14909&os=Vista&via=pppoA
Also found some useful advice on Noise margin/attenuation (maybe others will find hekpful):-
http://www.kitz.co.uk/adsl/linestats.htm
And how to improve your line:-
http://www.kitz.co.uk/adsl/socket.htm
Will be keeping mine all 'as is' until I get a report back from Plusnet Faults Team
Community Veteran
Posts: 26,722
Thanks: 936
Fixes: 10
Registered: ‎10-04-2007

Re: Apparent Throttling of Speed on Plusnet Pro

If the router is set for 1492 and MTU path discovery is working correctly the PC will automatically cut back to 1492.
You might get a tiny bit more out of the line if you try 1500.
jelv (a.k.a Spoon Whittler)
   Why I have left Plusnet (warning: long post!)   
Broadband: Andrews & Arnold Home::1 (FTTC 80/20)
Line rental: Pulse 8 Home Line Rental (£13/month)
Mobile: iD mobile (£4/month)
baker2009
Dabbler
Posts: 13
Registered: ‎12-04-2012

Re: Apparent Throttling of Speed on Plusnet Pro

OK, great. Will wait until faults team come back to me and see what they say about the 'Apparent Throttling' and then  start tweaking if required.
Thanks again.
Jojo - any updates/advice? Is this perhaps just part of the Plusnet Traffic Shaping policy during busy periods despite me having the 'Pro' add on?
OK - As I write this, just lost DSL line sync at 12:48L, reconnected automatically at 12:51L - are they doing something to my line? Resynced higher now though:-
ADSL Link                Downstream Upstream
Connection Speed   17284 kbps   916 kbps
Line Attenuation       23.6 db         14.6 db
Noise Margin            5.7 db            6.5 db
And then just lost it again at 12:53L, reconnected at 12:55L now showing:-
ADSL Link               Downstream Upstream
Connection Speed  17249 kbps   915 kbps
Line Attenuation      23.6 db         14.6 db
Noise Margin           5.8 db           6.5 db
Speeds now stable at 14MBps download/25ms ping and no throttling.....will report back on the next instance of line throttling....
I see I am not the only one with this issue! > http://community.plus.net/forum/index.php/topic,103930.0.html
jojopillo
Grafter
Posts: 9,786
Registered: ‎16-06-2010

Re: Apparent Throttling of Speed on Plusnet Pro

HI baker2009,
There's no traffic shaping or rate limits on Pro that would restrict your throughput. The link you quote may seem similar but is definitely different. Your Traffic management profile is correct, their's wasn't. This has just been tested by our faults team and raised to our suppliers as a suspected network issue. We'll have to see what they come back with.
Jojo Smiley
baker2009
Dabbler
Posts: 13
Registered: ‎12-04-2012

Re: Apparent Throttling of Speed on Plusnet Pro

Jojo,
OK, fair point.  I'll wait and see.  Currently speeds are normal, will let you know when it drops again.
Thanks.
Gavin