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TP Link TD-W9970 Slow Downloads

jameson_uk
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Posts: 11
Registered: ‎27-05-2020

TP Link TD-W9970 Slow Downloads

I want to replace the Plusnet Hub with my own router and have got a TP Link TD-W9970 which I intend to use in bridge mode.

To start with I have just switched the router for the TP Link one and the stats say my downstream connection rate is 55,874 kbps but when I try a speed test I am getting downloads of between 4 Mbps and 6 Mbps.   Oddly my upload speeds are around 18 Mbps.

Switching the Plusnet hub back I am getting download speeds of 45 Mbps + and the same upload speed of about 18 Mbps.

I have configured everything I think I need to (the TP Link seems to have plusnet settings anyway but the VLAN is set to 101 and the PPPOE details are my plusnet ones).

 

What I am missing that seems to be limiting me down to ADSL speeds?

Edit: Also just to clarify this is wired (albeit via a powerline adaptor) WiFi is disabled.

24 REPLIES 24
MisterW
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Re: TP Link TD-W9970 Slow Downloads

Hi @jameson_uk  looks like the W9970 is synching at a pretty good rate. I've used one in bridge mode for quite a while on a 40/10 connection and not seen any problems with throughput. I've never used it as a router though, it is a pretty low spec device so that might be the issue. I would suggest setting it up in bridge mode and connecting to the WAN port on the Hub one and see what the speeds look like. I've not used a Hub one for a while but I think that should work without any configuration changes. That should prove whether it's the W9970 itself causing the problem or just the fact that its not very good in router mode. If the throughput is ok then you can go on with your plan...

Baldrick1
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Re: TP Link TD-W9970 Slow Downloads


@jameson_uk wrote:

I want to replace the Plusnet Hub with my own router and have got a TP Link TD-W9970 which I intend to use in bridge mode.


This is confusing.

Do you want to get rid of your Plusnet Hub, as in replace it, or use both as in bridge mode?

If the latter then do you want to use the 9970 as a bridge modem, if so why, there’s nothing particularly wrong with the modem section of Plusnet hubs apart from the inability to extract stats?

Alternatively do you want to use it as a bridge router a.k.a Access Point  mode, in which case I’m afraid that it’s a pretty poor choice of alternative device?

.

 

jameson_uk
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Registered: ‎27-05-2020

Re: TP Link TD-W9970 Slow Downloads


@Baldrick1 wrote:

This is confusing.

Do you want to get rid of your Plusnet Hub, as in replace it, or use both as in bridge mode?

If the latter then do you want to use the 9970 as a bridge modem, if so why, there’s nothing particularly wrong with the modem section of Plusnet hubs apart from the inability to extract stats?

 


I want to get rid of the Hub One. I have an EdgeRouter and I want to use the TP Link device as a modem in bridge mode (I would use the Hub if it could work in bridge mode and I don't want double NAT)

jameson_uk
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Registered: ‎27-05-2020

Re: TP Link TD-W9970 Slow Downloads


@MisterW wrote:

Hi @jameson_uk  looks like the W9970 is synching at a pretty good rate. I've used one in bridge mode for quite a while on a 40/10 connection and not seen any problems with throughput. I've never used it as a router though, it is a pretty low spec device so that might be the issue. I would suggest setting it up in bridge mode and connecting to the WAN port on the Hub one and see what the speeds look like. I've not used a Hub one for a while but I think that should work without any configuration changes. That should prove whether it's the W9970 itself causing the problem or just the fact that its not very good in router mode. If the throughput is ok then you can go on with your plan...


I will give it a go later but last night I did have a look at the stats and noticed I am seeing lots and lots of errors in the downstream connection.    Obviously I don't see any stats on the Hub One to compare but this does seem to be a problem but there isn't really much more to go on, other than the fact there are errors...

VDSL.png

MisterW
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Re: TP Link TD-W9970 Slow Downloads

The W9970 is generally accepted as having a pretty good modem, even compared to the HG612 https://kitz.co.uk/routers/tplink_TD-W9970_review.htm. The Hub one has a lantiq chipset whereas the 9970 is broadcom.

Those stats look like the 9970 is trying a bit hard to maintain too high sync on the downstream. Its only got a 5.1db margin whereas you'd normally expect 6db. The problem is going to be that when in bridge mode you'll need to connect directly to another LAN port to see the stats. 

jameson_uk
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Registered: ‎27-05-2020

Re: TP Link TD-W9970 Slow Downloads


@MisterW wrote:

The W9970 is generally accepted as having a pretty good modem, even compared to the HG612 https://kitz.co.uk/routers/tplink_TD-W9970_review.htm. The Hub one has a lantiq chipset whereas the 9970 is broadcom.

Those stats look like the 9970 is trying a bit hard to maintain too high sync on the downstream. Its only got a 5.1db margin whereas you'd normally expect 6db. The problem is going to be that when in bridge mode you'll need to connect directly to another LAN port to see the stats. 


Is SNR something that is measured by the modem or sent from the exchange?   Is it likely that connecting up to the engineering socket might change this value?  Essentially is the SNR an attribute of my line or can I influence it?

MisterW
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Re: TP Link TD-W9970 Slow Downloads

SNR is 'signal to noise ratio' . As the SNR reduces so errors will increase. In general, for any particular line, as sync speed increases, SNR decreases. SNR also changes over the day as external factors affect noise on the line.

There's a good explanation here https://kitz.co.uk/adsl/linestats_explanation.htm

When a router starts the dsl synchronising procedure, it negotiates the fastest speed possible with a (normally) 6db SNR. That's known as target SNR margin and is preset by the BT DLM. The 6db is set to give a reasonable SNR that will minimize errors whilst attaining a reasonably fast  speed that the line can achieve. Having synched at a particular speed, should external noise reduce the actual SNR, then errors will increase, until it gets to a point where the error rate gets so high, that the line resynchs at a lower speed to get back to the 6db target.

 Is it likely that connecting up to the engineering socket might change this value?  Essentially is the SNR an attribute of my line or can I influence it?

If you have any extension wiring then yes, connecting to the test socket will eliminate the potential for noise to be introduced by that wiring.

In essence your line characteristics, length (distance to the cabinet) and condition, govern what speed will be obtainable at the 6db target. Longer or old wiring will reduce the signal strength and thus speed will be reduced to maintain the 6db target.

bill888
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Re: TP Link TD-W9970 Slow Downloads

fwiw, I would rerun the wired speed test without your powerline adapters to see if there is any improvement in download speed?

jameson_uk
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Re: TP Link TD-W9970 Slow Downloads

So I have had chance to do some more playing around and this is intermittent.   Bridge mode or not the same problem is there.

 

Yesterday I set everything up and was getting a nice 52 Mbps speed consistently, very few errors and all was good.   This morning it was still fine but around lunch time my download speed dropped to about 1.5 Mbps 😭.   I logged on to the modem and say the SNR margin was down to 0.8 dB and there were lots of errors.

 

So I went and plugged the modem into the engineering socket.   I got about 55 Mbps and a SNR margin on 5.8 dB.   I watched this for 20 minutes and the SNR margin fluctuated a between about 5.8 dB and 6.4 dB but was generally about 6.1 dB with a handful of errors.

I then tried the outside of the master socket and I did get a slower sync speed (~ 44 Mbps) and an SNR margin of 6.1 dB.   Watched this for about 15 minutes and SNR margin fluctuated a little.

So back to the extension I have run from the master socket and this time I got a sync at about 55 Mbps an a SNR margin of 6.7 dB.   I watched this for 20 minutes and it goes as high as 7.1 dB.

So I left it a while and occasionally tested download speeds.   I have a had a couple of times when it has dropped to  become noticeably slow and on these occasions the SNR margin has dropped down (not as bad as 0.8 dB but to 4.0 - 5.5 dB).

 

These tests have all been wired to rule out anything and I have just ran a speed check (via WiFi) and got 50 Mbps.

I suspect at some point the speed is going to drop near to zero again.

 

Oddly the upstream connection always seems to have a SNR margin or around 6.8 dB + and it looks like this is actually being capped at 20,000 kbps and never seems to drop (I have seen cases where a speed test has given me 4.5 Mbps down and 18.4 Mbps up)

 

What can I do to debug this (could this be a line fault ?)

LaurenB
Plusnet Help Team
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Re: TP Link TD-W9970 Slow Downloads

Together with our network partners at Openreach we are prioritising customers who don’t have a phone line or broadband connection, meaning there might be a delay in Speed Faults being fixed.

 

In the meantime, please raise your speed fault online at faults.plus.net.

If this post resolved your issue please click the 'This fixed my problem' button
 Lauren Barry
 Plusnet Help Team
MisterW
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Re: TP Link TD-W9970 Slow Downloads

So I went and plugged the modem into the engineering socket.   I got about 55 Mbps and a SNR margin on 5.8 dB.   I watched this for 20 minutes and the SNR margin fluctuated a between about 5.8 dB and 6.4 dB but was generally about 6.1 dB with a handful of errors.

I then tried the outside of the master socket and I did get a slower sync speed (~ 44 Mbps) and an SNR margin of 6.1 dB.   Watched this for about 15 minutes and SNR margin fluctuated a little.

So back to the extension I have run from the master socket and this time I got a sync at about 55 Mbps an a SNR margin of 6.7 dB.   I watched this for 20 minutes and it goes as high as 7.1 dB.

So I left it a while and occasionally tested download speeds.   I have a had a couple of times when it has dropped to  become noticeably slow and on these occasions the SNR margin has dropped down (not as bad as 0.8 dB but to 4.0 - 5.5 dB)

@jameson_uk that does look like a line issue, although it may well be an internal problem.

You need to leave the modem plugged into the test socket for some time and confirm that the problem still exists to rule out any internal wiring issues.

Does the trigger of the low speed correspond to any phone calls ? 

jameson_uk
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Registered: ‎27-05-2020

Re: TP Link TD-W9970 Slow Downloads


@MisterW wrote:

that does look like a line issue, although it may well be an internal problem.

You need to leave the modem plugged into the test socket for some time and confirm that the problem still exists to rule out any internal wiring issues.

Does the trigger of the low speed correspond to any phone calls ? 


I will try but it is difficult to run things that way (hence the extension....).   Also it is a pain to tell when it is happening unless you happen to notice things going slow.   I might try and script something to check the speed every five minutes.

It certainly isn't related to outgoing calls as we don't have a phone plugged in.   I will try and call the landline and see what happens.   What else might suddenly cause the SNR margin to drop (presumably this will effectively equate to an increase in noise?)

 

What internally might cause drops in the SNR margin ?

MisterW
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Re: TP Link TD-W9970 Slow Downloads

What internally might cause drops in the SNR margin ?

Faulty cable , bad socket , bad connection to socket, electrical noise pickup etc

jameson_uk
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Registered: ‎27-05-2020

Re: TP Link TD-W9970 Slow Downloads

So things have been up and down a bit.   Earlier today the modem completely lost sync.   Rebooted it and it resynced at 55 Mbps but I was only seeing 4.5 Mbps but 10 minutes later I was seeing 48 Mbps speeds.

 

I am going to plug everything into the master socket but am I able to run any sort of line test or see any sort of historical stats fro the exchange side?