Bizarre speed changes

[#1]

I'm on Plusnet unlimited fibre (36Mbps). For some time now I've typically had a vsdl downstream sync speed of somewhere in the high 40s Mbps. Over the past few days I've been throttled back to the point where I'm now at an actual of 17998Kbps. Investigation showed that the sync speed was sometimes dropping dramatically to something not much above 20Mbps. We first noticed this when the wind was high, and it seemed to be coincident with crackle on the phone line so I assumed we were experiencing an intermittent fault in the overhead wiring to our house. As of today, things have changed: currently the sync speed is in the mid 30s but if I pick up a phone (either of the two we have) it increases to the mid 40s after a second or two. When I put the phone back on the cradle it drops again to the mid 30s. I'm using a Vigor 2860 vdsl router, which is how I can get the stats. I've rebooted the router (it was going between mid 40s and low 20s before I did that, so it made a difference but didn't change the behaviour), I've gone back to the master test socket (although that meant substituting the faceplate filter with an in-line one, which seemed to reduce the overall line speed a bit) and unplugged both phones and one phone at a time; but whatever I do I always with the same general effect: if the phone line is being used the speed goes up, and if it isn't it drops again. Has anyone any idea what could cause this effect? Could it be a a side-effect of the intermittent fault, with a dodgy connection or wire somewhere? It's driving me nuts!

[#2]

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@gco wrote:

Could it be a a side-effect of the intermittent fault, with a dodgy connection or wire somewhere? It's driving me nuts!

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In a word, yes.

It sounds like a high resistance joint that improves as soon as there is a slight load put on the line by the phone circuit. In the electonics world we used to call this slight current requirement through a connector 'wetting current'. The drop in speed can be caused by the loss of one of the two lines into your house (broadband will work at reduced speed on only one wire) because of a high resistance joint giving you insufficient wetting current.

Hopefully a Plusnet staffer will pick this post up soon and do the necessary for you.

[#3]

Hi @gco,

I'm really sorry to hear that you've been experiencing these issues. I've tested your line today and we're detecting a potential fault with equipment in use. Before we can proceed further with our investigation, we'll need to rule out that the internal equipment is causing the issue and to do so, we'll need you to go through our online troubleshooting guide, which can be found here.

I can see that you've already done some troubleshooting from your end of things already, but we'd just need to rule everything out before progressing to the next stage of the investigation. If these troubleshooting steps fail to resolve the fault then please let us know and we will pick this back up for further review as soon as possible.

[#4]

Thanks for picking this up.

In terms of the four steps of your online troubleshooting guide:

1. Dial tone is fine. As I said, there were some crackles associated with dramatic drops in sync speed, but the line is quiet (I've done a quiet test too). There might be a very occasional single click/crackle.

2. Wires are all plugged in properly.

3. I've tried the router plugged into the master socket. I had to use a filter to break out a suitable connection from the single master socket, but that should provide a straight-through connection to the router. This resulted in a slight reduction in sync speed, but the fault was still there and the sync speed could be varied by plugging in a phone to the filtered connection and lifting and replacing the receiver.

4. The problem is still there.

A line test was done a couple of days ago and revealed no problems, but that was before the change in behaviour I observed today. I'm not sure what your tests have revealed. If you can advise who should do what next that would be helpful. Note that my line is through another provider (AdePT).

[#5]

By 'Master Socket' do you mean the Test Socket? That's the one that you access by taking the faceplate off the Master socket. Taking the faceplate off disconnects all extension wiring.

[#6]

Hi @gco,

Thanks for getting back in touch. I've raised a ticket regarding this fault on your account, which can be found here.

Once you've been able to respond, please let us know so we can pick this back up for further review.

[#7]

Yes, sorry: I mean the test socket. I thought I had corrected this before I submitted, but clearly I was mistaken. In my installation it is necessary to take two layers off (mk3 faceplate) in order to take the filter out of the equation.

[#8]

Hi.

I've responded to the ticket with some dates.

Gavin.

[#9]

Cheers Gavin, 

I've just made the booking and have updated the ticket with details: https://www.plus.net/wizard/?p=view_question&id=188377403

[#10]

Hi.

Just to thank you for arranging an engineer appointment. A potentially dodgy connection was identified and re-made and the sync speed stabilised. After this, ping latency increased and true data transfer rates fell off, but I guess that's because interleaving was activated. Last night DLM reset the line to fast mode and I'm now getting test speeds exceeding 35Mbps and 9Mbps for downstream and upstream respectively, so I'm a happy customer!

All the best,

Gavin.

[#11]

Hi @gco 

No worries, glad it's all sorted! 

Give us a yell if there is anything else we can do for you. 

Kind Regards, 

MoR