Minimum Guaranteed Speed and DLM reset

[#1]

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@zenza wrote:

I did that last time and got a call from a CSC Analyst at plusnet (name was redacted above). Spoke with him for less than 5 minutes. He immediately reset the DLM. Had 20+ mbps ever since. Well until the DLM started knocking down my speed a nudge almost every night for the last couple of weeks.

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It will do that, in an attempt to maintain a stable connection.

[#2]

Coming on here was my way of trying get around customer support - in the hope that somebody at Plusnet might see my post. 

My experience last time was enough thanks very much. Having to teach a support person how to type an underscore on a keyboard was the first step in a 50 minute call that got me nowhere. 

Thanks for all your help anyway everybody - very very much appreciated.

[#3]

My idea of a stable connection is definitely not the same as the DLM. 24mbps with a bit of packet loss is way better than an utterly [-Censored-] sync speed with no packet loss. 

I remember many years ago being with an ISP called BeThere (I think that was their name) - they gave you the option to manage your own connection profile. Ahh the good old days. Probably before DLM was invented. 

[#4]

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@jab1 wrote:

Fair enough, @zenza . A 12 month wait for FTTP would have me asking for a better solution than a DLM reset every month, but if that is what you want -ring Customer Support - asking on here will probably mean you wait a month for a response.

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Xmas 2026, 24 months, not 12 months - but I'm very patient(ish).  😉  

[#5]

You have the patience of all the saints combined - If I has to wait until then, I'd be exploding, never mind fuming, @zenza .

[#6]

There is zero point chasing DLM resets in the presence of a line fault / instability. Reset -> faster sync -> more disconnects -> DLM steps in to reduce speed to improve reliability.

The big question is do you have a faulty line or a source of RFI?

The line attenuation is little different to mine which delivers over 60mbps. Something is significantly wrong here. Would you know if you’ve had a d-side swap? Have all of the joints been remade?

Are you FTTC or SOGEA? If FTTC have you listened to the line with a telephone handset?

[#7]

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@Townman wrote:
There is zero point chasing DLM resets in the presence of a line fault / instability. Reset -> faster sync -> more disconnects -> DLM steps in to reduce speed to improve reliability.

The big question is do you have a faulty line or a source of RFI?

The line attenuation is little different to mine which delivers over 60mbps. Something is significantly wrong here. Would you know if you’ve had a d-side swap? Have all of the joints been remade?

Are you FTTC or SOGEA? If FTTC have you listened to the line with a telephone handset?

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As stated before - the line has been tested by Openreach before. The line is old and poor quality - everything that can be done has been done and their final comments were that they would have to replace the copper line to the cabinet (600 yards away) and they would not carry out this work - certainly not before the full fibre rollout which is scheduled for before Xmas 2026. 

We no longer have telephone capabilities since we swapped to Plusnet from BT. Prior to the swap though, a few months ago, the telephone sounded OK.  No audible noise on the line. 

 Previously a DLM reset by BT/Openreach and Plusnet has brought the line back up to 24mbps every single time. This line has been like this for 5 years at least. Copper to the pole has been swapped and everything that can be done has been done. 

Last time this occurred with Openreach they didn't even bother to send somebody out. They just did a DLM reset. 

I will keep monitoring the line. Based on past experience - if nobody does a DLM reset the line will probably right itself within 6 to 8 weeks anyway.

Considering the number of times Openreach have been out to fix this in the past I'm pretty sure that if a D-side swap was available then they would have done it.

"There is zero point chasing DLM resets in the presence of a line fault / instability."  --  funny, it's worked every time so far. Not a permanent solution I admit - but better than nothing and certainly not me that came up with the idea (that'd be Openreach). 

PS: if you are wondering why I swapped from BT to Plusnet only to have pretty much the same service, its because I got sick of BT calling me on a regular basis trying to sell me voip and God knows what else.

[#8]

@Townman 

The line attenuation is little different to mine which delivers over 60mbps

I would suggest your experience is an exception rather than the norm, over the years I have been on this forum I have noted posted router stats and created short list of average Maximum Data Rate against line attenuation.

Typica Line attenuation to Maximum data rate
0.7 Km from cabinet Maximum Data rate 35,000 Mbps; line attenuation 21.9
0.6 Km from cabinet Maximum Data rate 44,450 Mbps; line attenuation 19.1
0.5 Km from cabinet Maximum Data rate 50,415 Mbps; Line Attenuation 15.7
0.3 Km from cabinet Maximum Data rate 89.472 Mbps; line attenuation 11.6

https://www.increasebroadbandspeed.co.uk/chart-of-bt-fttc-vdsl2-speed-against-distance-from-the-cabi...

As we both know many factors can effect Line Attenuation

[#9]

Define “it worked”.

Resetting the DLM puts it back into training mode. It starts at 24mbps and the will wind the speed back each time sync is lost. And then you’ll be asking for another reset.

[#10]

Dan …

DSL uptime:47 Days 7 Hrs 19 Mins
Data rate:10.088 Mbps / 72.435 Mbps
Maximum data rate:10.337 Mbps / 77.109 Mbps
Noise margin:6.8 / 4.3
Line attenuation:9.2 / 20.0

[#11]

Not disputing your stats, but you are a distance from the FTTC cab, your upload speed is low

I rebooted my Hub Two recently

DSL uptime:14 Days 15 Hrs 49 Mins
Data rate:17.13 Mbps / 79.999 Mbps
Maximum data rate:16.398 Mbps / 89.755 Mbps
Noise margin:4.4 / 5.0
Line attenuation:6.3 / 11.4
Signal attenuation:6.3 / 12.0

[#12]

Just spoken to support. To a much much more helpful person than last time.  

Bottom line, a DLM reset has just been done and a two way conversation is now in place so we can monitor the situation over the next few weeks. All good (for now). I'll keep you posted.

[#13 · Accepted solution]

@zenza I was about to check this for you but you called up and spoke to Kane and it is being dealt with and monitored by him.