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Unable to investigate latency of up to 100ms?

mossywell
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Registered: ‎08-09-2016

Unable to investigate latency of up to 100ms?

Hi, in early April, my latency went from 7ms (Fastpath) to 15ms (Interleaved) quite spontaneously. Then in early May it jumped again to 25ms. I got in touch with CS via Chat and they said that they cannot investigate latency issues under 100ms. 100MS???!!!! I can get that with an old modem!

 

Is this a new PN policy or has it always been the case and I was just unaware?

37 REPLIES 37
ejs
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Re: Unable to investigate latency of up to 100ms?

I don't know about the 100ms threshold.

Your latency changes may well be due to the DLM applying interleaving, perhaps at 15ms there was interleaving only on the downstream, and at 25ms it's on both the upstream and downstream, or there's more interleaving (with a higher delay). Neither Plusnet nor any other ISP can control the FTTC DLM to turn off interleaving. Presumably you are on an ECI cabinet, and your latency may decrease if and when Openreach re-introduce retransmission (G.INP).

mossywell
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Re: Unable to investigate latency of up to 100ms?

Thanks for the reply. Putting aside the tech (yes, you're right techncially but my OP is about policy - the latency I can fix), can anyone from PN confirm if it is now PN's policy not to investigate a sudden wired rise in latency from 7ms to (let's say) 99ms?

mossywell
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Re: Unable to investigate latency of up to 100ms?

Tumbleweed....

rongtw
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Re: Unable to investigate latency of up to 100ms?

its a bank holiday weekend , Staff are thin on the ground Shocked

I have never seen a 100ping requirement for a fault Huh

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mossywell
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Re: Unable to investigate latency of up to 100ms?

LOL. Yes, good point. Yes it was the first I've heard of it. Given that the forums seem to be really quiet at the moment, and the online chat takes about 30 minutes, I might just write a letter to Andy Baker and ask him for a definitive answer.

I'm still somewhat in a state of shock that PN think that non-investigation of what is clearly a problem is an acceptable answer.

Gandalf
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Re: Unable to investigate latency of up to 100ms?

Sorry to hear you're having problems.

We don't have a process on latency issues. If it's causing a problem we're here to help.

Testing your line isn't identifying the cause of that.

Sync Status In Sync
Downstream Speed 52.7 Mbps
Upstream Speed 20.0 Mbps

Are you using a wired or wireless connection?

From 31st October 2022, I no longer have a regular presence here as I’ve moved on to a new role.
Anoush Mortazavi
Plusnet
mossywell
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Re: Unable to investigate latency of up to 100ms?

Hi Gandalf,

Don't you hate it when the customer services people make things up to get rid of you?

 

Anyway, thanks for the reply. Here's the info:

 

1. Router: Asus DSL ac68u

2. Router config (DSL): Completely factory defaults

3. All tests are done using cat 5e cable directly connected to the router.

4. Router plugged into the wall socket

5. NTE is a Openreach MK4 (yes, 4 - the new ones that don't need a crimping tool)

6. There is no internal wiring - I disconnected it months ago (we never used the phone line)

7. Recent changes: none - the pattern you see is all spontaneous

 

8. Tests I do: a speed test every 15 minutes to the same speed test end point. And a ping every 60 seconds to www.ebay.co.uk (but the same pattern occurs for all sites).

 

Results uploaded.

 

Latency.PNG

 

 

Speed.PNG

Latency.png shows an increase from 7 to 15 on the 13th April and then a rise from 15 to 28 on the 6th May. I was on fastpath and now am on interleaved.

 

Speed.png: blue is sync speed (measured directly from the router using a script I wrote) and red is the speedtest. It shows a drop in speed on the 22nd May. If you are into correlations, take a look at the 28ms latency section - you'll see where it starts to improve a little on the 16th May but on the 22nd goes back up again to 28ms. This coincides with the speed drop.

 

You'll also notice that the sync speed has been gradually deteriorating since the 22nd March. (I thought this might correlate with the temperature in London, but it doesn't - my best sync speed was in March, but London was actually coolest in January this year.)

 

 

Something isn't right! (In the past 3 OR engineer visits in November / December last year, each time they said that there was no problem.)

 

Thanks for your help.

 

 

 

ejs
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Re: Unable to investigate latency of up to 100ms?


@mossywell wrote:

I'm still somewhat in a state of shock that PN think that non-investigation of what is clearly a problem is an acceptable answer.


Are you referring to your latency, of 25ms, or the hypothetical latency of 99ms?

I'd say 25ms is a non-problem.

So this turns out to be yet another person with a problem using one of those Asus models. I'd suggest using something with a decent VDSL2 modem (not most of the Asus models with their MediaTek DSL chipset).

A general reduction in speed over a long time could be due to increased crosstalk from more people on your cabinet switching to FTTC. With the problem exacerbated by the Asus modem.

Gandalf
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Re: Unable to investigate latency of up to 100ms?


@mossywell wrote:

Hi Gandalf,

Don't you hate it when the customer services people make things up to get rid of you?

I'll be sure to pass on internal feedback to the adviser(s) regarding that.

From 31st October 2022, I no longer have a regular presence here as I’ve moved on to a new role.
Anoush Mortazavi
Plusnet
mossywell
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Registered: ‎08-09-2016

Re: Unable to investigate latency of up to 100ms?



Are you referring to your latency, of 25ms, or the hypothetical latency of 99ms?

 

As per my OP, but no need to worry further - Gandalf has already confirmed that this is not PN's policy. 

 


So this turns out to be yet another person with a problem using one of those Asus models. I'd suggest using something with a decent VDSL2 modem (not most of the Asus models with their MediaTek DSL chipset).

A general reduction in speed over a long time could be due to increased crosstalk from more people on your cabinet switching to FTTC. With the problem exacerbated by the Asus modem.


The increase in users theorem has merit but fails to explain the improvement between December and March.

 

Re your dislike of Mediatek chipsets, I'd need to see a statistically significant result from a prospective study to take that comment on board. (A chi squared test of independence would suffice because it includes all those with Mediatek chipsets that don't have problem - which is critical to any "proof" - as well as non-Mediatek people.) Moreover, as with the "increase in users" theorem, it doesn't explain the improvement between December and March. 

 

 

EDIT: Oh yes, forgot to mention, it may all be irrelevant anyway as I may be getting a mesh wifi in which case I'll probably use the Plus One (though IFAIK it doesn't support modem-only so I might have to do a double NAT - not really looked into it but it won't be difficult) or get a dedicated modem.

mossywell
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Registered: ‎08-09-2016

Re: Unable to investigate latency of up to 100ms?


@Gandalf wrote:

I'll be sure to pass on internal feedback to the adviser(s) regarding that.


Splendid! Thank you very much.

ejs
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Re: Unable to investigate latency of up to 100ms?

Regardless of anyone's opinion of these Asus devices, you ought to try a different device using a process of elimination to rule it out as being part of the problem."It was working fine until it wasn't" doesn't imply that it's not the problem. Unfortunately waiting for the DLM to make any changes such as reducing the interleaving level could take a long and uncertain amount of time.

Openreach do sometimes make changes to their network, making changes to the cabinet firmware or operation or how the DLM operates. Sometimes the general public who monitor their DSL stats will notice, other times there'll be nothing visible. If a third-party device that hasn't been tested to meet the requirements of BT SIN 498 doesn't work as well afterwards, Openreach probably aren't going to do anything about it.

As for using additional wifi access points, mesh or otherwise, there wouldn't be any additional NAT if the devices are connected to the LAN and functioning as wireless access points.

dfunked
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Re: Unable to investigate latency of up to 100ms?

I don't really hang out here enough to notice a trend, but have there really been that many posts from Asus router users with this issue?...

Another way of looking at it is maybe if you're commited enough to spend that kind of money on a router, you're possibly more technically inclined and likelier to see poor pings and know where to start looking to get to the bottom of this.

Who is more likely to report or even perceive a problem with 30ms pings? Netflix streaming Joe with his freebie technicolour router, or gaming Dave with his £100+ router?...
ejs
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Re: Unable to investigate latency of up to 100ms?

No problem with any Internet activity has actually been reported here - only the change in measured performance metrics.

Even one of mossywell's previous posts noticed the problem with the line rate not being reported properly, I know we've seen instances where the BT IP Profile doesn't update when using an Asus.