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Author Topic: Massive download speed drop, upload stayed the same.  (Read 5231 times)

Ronski

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Massive download speed drop, upload stayed the same.
« on: October 14, 2013, 02:09:11 PM »

Our FTTC download speeds have slowed to a crawl, whilst upload has stayed the same. We're on a 40/10 package, and usually get around 38Mbps.

Speedtests carried out via wired connection on XP.

Speedtest.net test
Think Broadband test

All logs uploaded to Dropbox

It's a business line with Plus Net, and they have requested that I need connect a laptop directly to the modem and connect via a PPPoE session just to rule the internal network out. I still need to do this.


Any info will be helpful.

Edit: We've been on fast path since 27 August this year.
« Last Edit: October 14, 2013, 02:11:33 PM by Ronski »
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ryant704

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Re: Massive download speed drop, upload stayed the same.
« Reply #1 on: October 14, 2013, 02:27:03 PM »

As I posted on the other thread it's probably due to the high error count but that isn't 100%.

You can see there is something interfering with your line on your QLN graphs... (reason for the errors I would imagine...).

08/10/2013

14/10/2013 (Todays)
« Last Edit: October 14, 2013, 02:35:11 PM by ryant704 »
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Ronski

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Re: Massive download speed drop, upload stayed the same.
« Reply #2 on: October 14, 2013, 03:26:05 PM »

We're on an industrial estate, the lines are not great, and they also come into the building right next to the 3 phrase supply and all the meters/switch gear.

Just done a quiet line test and that was perfect. Powered off the modem first, rather than just unplugging it.

We've now pretty much regained all the speed, but interleaving has kicked in - see attached

Plus Net say that BT are running some diagnostics, so we'll let them see what they come up with.

Strange how upload speed hasn't been affected though.
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Ronski

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Re: Massive download speed drop, upload stayed the same.
« Reply #3 on: October 15, 2013, 08:17:15 AM »

As expected I had even more severe interleaving applied this morning, this after several months with no interleaving, so something must of changed to cause the interference. Perhaps somebody else has had FTTC installed, and it's just crosstalk.



One thing this episode does indicate is just how good interleaving can be, we had a virtually unusable connection due we think to errors caused by interference as pointed out by ryant704. As soon as interleaving kicked in the connection was usable again, albeit slower and with a higher ping.
« Last Edit: October 15, 2013, 03:18:05 PM by Ronski »
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Chrysalis

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Re: Massive download speed drop, upload stayed the same.
« Reply #4 on: October 15, 2013, 12:36:07 PM »

well I wonder how good your connection would be if you had the same sync speed reduction via increase of snrm instead of FEC?  I personally think interleaving is overhyped.  Plus doubling someone's latency for long periods of time is nasty.
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ryant704

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Re: Massive download speed drop, upload stayed the same.
« Reply #5 on: October 15, 2013, 03:02:50 PM »

For some I'm putting this problem on the firmware (or part) as I've read/seen peoples graph and they are getting the same (not as worse as yours though!). Plusnet need to send out a broadband engineer then once hes been they should be able to request a REIN engineer.
« Last Edit: October 15, 2013, 03:25:11 PM by ryant704 »
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Chrysalis

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Re: Massive download speed drop, upload stayed the same.
« Reply #6 on: October 15, 2013, 03:16:10 PM »

Question was to ronski, in my view snrm increases can have very good affect on stability.
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Ronski

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Re: Massive download speed drop, upload stayed the same.
« Reply #7 on: October 15, 2013, 03:26:27 PM »

@ryant704, yes I had seen others posting that their interleaving had increased since the update.

@Chrysalis, now I come to think of it our snrm had been at 9dB for some time, looking at the graphs it went from 6 to 9dB on 27 August, the same time as we went on fast path, and yesterday it dropped to 6dB

Graphs attached.

I'll give Plus Net another day and then chase them up, as they did say 24 to 48 hours.

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ryant704

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Re: Massive download speed drop, upload stayed the same.
« Reply #8 on: October 15, 2013, 03:43:03 PM »

The 3db will come from the Interleaving change to fast path, hence why you are synced at a lower speed now at a 6 SNR margin and lost some sync speed. The more serve the interference becomes the DLM will increase DMT Symbols at the expense of noise (SNR margin).

We also need to remember Interleaving has a lot more factors to it than just the level, there was a big change with Interleaving with the last BLOB.

There was a discussion about it here maybe they have just changed how they achieve that level of Interleaving again.
« Last Edit: October 15, 2013, 03:45:06 PM by ryant704 »
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Ronski

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Re: Massive download speed drop, upload stayed the same.
« Reply #9 on: October 15, 2013, 03:51:30 PM »

I did post a fair bit in that thread as I was using that updated firmware at home, but I can't recall if the modem at work had that updated firmware, it's quite possible it did.

Unfortunately a lot of the technical stuff goes straight over my head.
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NewtronStar

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Re: Massive download speed drop, upload stayed the same.
« Reply #10 on: October 18, 2013, 07:33:04 PM »

I did post a fair bit in that thread as I was using that updated firmware at home, but I can't recall if the modem at work had that updated firmware, it's quite possible it did.

Unfortunately a lot of the technical stuff goes straight over my head.

 :D Yeah Ronski there is to much information in the stats for some of us to get to grips with
someone needs to do an A - Z tutorial on each of them only just starting to understand D: (interleaving Depth)  :P
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