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Fibre Unlimited speed issue - probably not a fault.

nafester
Dabbler
Posts: 10
Registered: 13-03-2013

Fibre Unlimited speed issue - probably not a fault.

Hiya,
I've noticed that the speed and ping that I've been getting are a fair bit worse (while still being good) than they were in the initial week. I understand that the first week is feeling out what my line is capable of, but it seemed to be very stable in that week, then after it all got finalised it took a bit of a dive.
From day one I was getting about 65mbit (between 7 and 8mbyte/s downloads from Steam), and often 7ms ping on Battlefield 3 servers. After the intro week I've been getting 55mbit (or about 6.5mbyte/s) and about 15ms - talk about your first-world problems, right? Still, I was wondering if some tinkering could be done on my account to improve that.
I've not done the whole bypassing of the router, running the cable straight from the Openreach box to my PC as it seems very unlikely to be a problem with the 582n. I am wired in to the 582n though.  I tried to find SNR stats but couldn't, the guide in the sticky post didn't seem to apply here, I'm guessing SNR stats are available only via the router on an ADSL connection?
Anyway, any advice appreciated!
edit: Oh and a quick question, I reset the router every now and then (every few days tops) just to see if things improve and I've noticed it takes minutes for the 582n to get a connection. The DSL light on the Openreach is very quick to light up, I then power up the 582n and it often takes a good 5minutes or more to get broadband up and running again. This seems like a long time, is that normal?
16 REPLIES
Highlighted
Community Veteran
Posts: 3,380
Thanks: 4
Registered: 18-01-2013

Re: Fibre Unlimited speed issue - probably not a fault.

Over time my connection slows down from 72Mb to 60-65Mb
A reboot of the modem (not router) normally pushes me back up for another couple of weeks.
My pings seem to stay stable though.
5 minutes is pretty normal on a "cold boot" - it took me around 8 minutes the other day when I restarted both the modem and router before I was back online although I do use a TP-Link router rather than the one supplied by PN. A normal router reboot usually takes no longer thank 20-30 seconds to sync back up.
nafester
Dabbler
Posts: 10
Registered: 13-03-2013

Re: Fibre Unlimited speed issue - probably not a fault.

Unfortunately I've not been able to see any improvement on reboots. Or, more precisely, I might see it drop below a 55mbit and restart will get it back up to 55mbit again but I've not found any way to get it back to the 65 I was getting on the first week :/.
Community Veteran
Posts: 3,380
Thanks: 4
Registered: 18-01-2013

Re: Fibre Unlimited speed issue - probably not a fault.

My profile has moved around a bit over the past 2-3 months. It started off at around 72Mb, dropped to 68Mb and is currently at 75Mb.
It appears fairly dynamic as well - I've not noticed any disconnections or reboots when the profile speed changes.
With a bit of luck one of the staff on here will have a peek at it for you and see if it needs a manual reset or something.
nafester
Dabbler
Posts: 10
Registered: 13-03-2013

Re: Fibre Unlimited speed issue - probably not a fault.

That's what I'm hoping! Smiley
hymermanbill
Grafter
Posts: 25
Registered: 30-09-2012

Re: Fibre Unlimited speed issue - probably not a fault.

My Fibre was Installed last November, I started with a 49mb connection that stayed for a week or so and that then dropped to 46.3mb which was consistent for a month or so. Then the speed started to sink slowly and eventually settled at between 37 and 39mb. No reasons given no answers available nobody seems interested. Its fine it does what I want very well but it is annoying that it is slower than it started off at and slower than it was after the settling in 10 days.
Community Veteran
Posts: 19,101
Thanks: 443
Fixes: 21
Registered: 31-08-2007

Re: Fibre Unlimited speed issue - probably not a fault.

Don't go re-boooting the BT modem unnecessarily, it can give you a worse sync speed than you had, it can also turn on/increase interleaving with resultant longer pings and there is nothing that can be done about that until the Fibre DLM decided to change it.
Likewise don't reboot the Router unless you really need to.
If you want/need to reboot then it's best to log in to the Router first and click Disconnect to drop your PPP session. Power down the Router next if it's the Modem you want to restart. Then power off the modem for at least an hour. Then power up the modem, wait until sync is established and power up the Router, log in and click Connect. Try and do that in Daylight hours as well, when interference levels are generally lower.
Interference/Noise, which can be caused by many different things, is usually the cause for lower sync speeds being seen after a period of time. The sources for example could be (intermittent) line problems, static (lightning), electrical interference, or just an increased number of users connected to your Cab - effects are often greater on the longer lines (this by the way applies to all forms of xDSL). The increased noise can cause a resync, this is often at a lower speed.
On Fibre, the easiest way to check what's happening to your sync speed, is to check the BT IP Profile by running the BTw Speedtest.
Log in to the Router, in the Internet box, click Disconnect to drop the PPP Internet session (this is not the sync), wait 30 seconds the click Connect. This should ensure the relevant servers are updated with the current sync speeds.
Then run the BTw Performance test (ignore the red preamble except make sure no other programs are using the Internet) and at the end of the first run, click the Further Diagnostics button, enter just your Phone number and Run the Further Diagnostics Test.
Do a Copy and Paste of the results and post here (no need to grab an image).
x47c
Grafter
Posts: 878
Registered: 14-08-2009

Re: Fibre Unlimited speed issue - probably not a fault.


A slowly sinking speed on FTTC is likely to be an example of cable cross talk.
FTTC is more prone to this than ADSL due to the higher frequencies used.
Cable cross talk is noise induced in your line pair from other FTTC activated lines within the same cable bundle of perhaps 100 line pairs in the physical cable.
Your line will be affected by others just as their's is affected by yours.
So as more and more lines get connected to a particular cabinet I would indeed expect speeds obtained by the early connectors to reduce from that originally obtained. Those later connectors will not to change by as much as their iniital speeds are obtained already with cross talk present in the cable from the pre-exisitng users.
To reduce the effect of cross talk in the cables BT have to keep the power levels output for the FTTC signal much lower than for ADSL.
Hence wheras the ADSL signal of some use will reach out to homes around 4Km at max - FTTC will only just reach out to around 2km from the cabinet at max.
As I said it was not seen on ADSL though it was probably there to a small extent but not noticeable to users. I think/recall that BT did try and ensure it was kept to a minimum by reducing the power for those very short lines which did not require the full power to be used to ensure they did not drown out the signal for the people at the far end of the line.
nafester
Dabbler
Posts: 10
Registered: 13-03-2013

Re: Fibre Unlimited speed issue - probably not a fault.

Hi Anotherone, here's the info:
Download speedachieved during the test was - 51.28 Mbps
For your connection, the acceptable range of speedsis 16 Mbps-57.49 Mbps .
Additional Information:
IP Profile for your line is - 57.49 Mbps
Upload speed achieved during the test was - 9.57Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps
One thing I should probably make clear, I've only had this connection for 3 weeks. The first week (or 10 days, the settling in period basically) I was getting about 65-68mbit down and about 14mbit up - immediately following that settling in period, I ended up with these lower speeds. Wouldn't that suggest that rather than cross talk, it's simply some settings that need tweaking?
Anyway, thanks for all the advice so far everyone.
Community Veteran
Posts: 19,101
Thanks: 443
Fixes: 21
Registered: 31-08-2007

Re: Fibre Unlimited speed issue - probably not a fault.

Sorry to have to disagree with you there x47c but it is/was very evident on ADSL as well, as early adopters on longer lines would be able to verify. The cross-talk which as you rightly say appears as noise on adjacent circuits and as I said above
Quote
(this by the way applies to all forms of xDSL)
and I can also verify from personal & practical experience it is still evident today, and so can anyone else on a longer line who runs their modem on a UPS - ask them what happens during a power cut! I can sync at 8128 (20CN) on a 3km line - the "noise" has disappeared.
@nafester
This "10 days" unfortunately gives people a misleading impression. On ADSL it is the length of time that the Exchange DLM monitors sync speed and sets the MSR - the lowest sync speed seen during that time, from which the FTR - Fault Threshold Rate is derived. On Fibre, there is no such thing. The FTR is pre-determined by the product type. The 10 days (on all products) is the period of time during which BTw/OR will not investigate most faults, there would be insufficient line data to come to significant conclusions in most cases.
Depending on line conditions, Fibre DLM can be quite aggressive within the first 24hrs if it detects severe instability, otherwise it waits until the 2nd day before it decides whether to impose any limits. Thereafter, as with ADSL, it monitors the line and will make adjustments depending on the prevailing conditions. However Fibre DLM cannot be "tweaked" in the way that certain parameters can be on 21CN for example, nor will Openreach do "line resets" (except perhaps after line repairs etc.).
As with any xDSL connection, interference/noise can come and go, so you may had synced at a speed lower than your line might be able to sustain the greater part of the time. If that were the case, DLM may up your sync speed in due course, but that's by no means guaranteed. If things seem stable, I'd be inclined to leave it alone especially if you have been "rebooting" already which DLM could well have seen as some form of instability. Otherwise if you want to try, I'd give it a week of no tampering first, try the method I described above leaving the modem off for an hour.  It may not give any improvement,  there's always the possibility it may give a worse result.
Edit: forgot to ask, do you know how far you are from the Cab? What was your estimated speed?
nafester
Dabbler
Posts: 10
Registered: 13-03-2013

Re: Fibre Unlimited speed issue - probably not a fault.

I was told by the engineer that the cabinet was at the end of my road, so that's about 300m I think. I was estimated to get 58mbit, so spot on to what I'm seeing now I guess, I guess it's just a little disappointing given that it was such a nice surprise getting 10mbit more on what seemed like a stable connection.
I'll leave the modem alone for a week or two and then perhaps try the hour reset thing. Am I understanding you right in that there's no way to get Plusnet to tweak settings to push the line a bit more? Coming from BeThere ADSL you could set your profile to be more or less aggressive, the trade off being stability - there's no option like that with this connection?
Once again, many thanks for your replies!
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Fibre Unlimited speed issue - probably not a fault.

Unfortunately there isn't on Fibre as yet. As the technology matures you'll no doubt see more tools start to become available but as yet we've no access to control anything on a fibre connection.
nafester
Dabbler
Posts: 10
Registered: 13-03-2013

Re: Fibre Unlimited speed issue - probably not a fault.

Hi Matt,
So in short, nothing I can really do to get back the speeds I was getting in the first week? And it's presumably not worth raising a case with tech support for?
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: Fibre Unlimited speed issue - probably not a fault.

In my opinion, if your line is running at the estimate, there is not going to be a lot that the Faults Team or our suppliers can do.
I've seen many cases where the connection speed is much faster after installation but it will drop as the line settles in.
Chris Pettitt
Cloud Environments Engineer
Community Veteran
Posts: 19,101
Thanks: 443
Fixes: 21
Registered: 31-08-2007

Re: Fibre Unlimited speed issue - probably not a fault.

And don't forget what I said about those changing noise conditions.
As Matt and Chris have said, nothing can be done on Fibre. Quite a lot can be tweaked on ADSL2+ (21CN) and not a lot on 20CN.