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Aspiring Contributor
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Message 1 of 3

Home Hub 5 noise margin stats falling and rising. Possible line fault?

Hi All.

 

I have been on BT Infinity 2 for a few days now and have seen a drop in my line speed almost daily. On day one I had speeds of D/60.5 and U/17.1 with noise margins of 6.0 on both upstream and downstream.

 

Over the last few days I've seen a drop of 2-3 Mbps almost every day. My connection today stands at D/49 and U/15.8.

 

I'm not all that surprised to see this drop as I previously had Sky Fibre (40/10) and that connection was often dropping down to 35 before recovering back to 40 a couple of weeks later.

 

Today while looking at the stats in HH5 on pressing refresh I saw a downstream noise margin drop from 6.5 to 3.9. This occurred around 17:30 and carried on fluctuating up and down for around 10 minutes. I have copied and pasted from the Helpdesk and you can see the big drops and gains in a short period:

 

5. VDSL uptime: 1 days, 13:55:51
6. Data rate: 15828 / 48980
7. Maximum data rate: 13896 / 52812
8. Noise margin: 4.3 / 4.2
9. Line attenuation: 0.0 / 19.1
10. Signal attenuation: 0.0 / 18.8

5. VDSL uptime: 1 days, 13:56:16
6. Data rate: 15828 / 48980
7. Maximum data rate: 13935 / 61170
8. Noise margin: 4.3 / 6.6
9. Line attenuation: 0.0 / 19.1
10. Signal attenuation: 0.0 / 18.8

5. VDSL uptime: 1 days, 13:56:44
6. Data rate: 15828 / 48980
7. Maximum data rate: 13944 / 52270
8. Noise margin: 4.3 / 4.0
9. Line attenuation: 0.0 / 19.1
10. Signal attenuation: 0.0 / 18.8

5. VDSL uptime: 1 days, 13:57:22
6. Data rate: 15828 / 48980
7. Maximum data rate: 13965 / 60907
8. Noise margin: 4.4 / 6.5
9. Line attenuation: 0.0 / 19.1
10. Signal attenuation: 0.0 / 18.8

 

As I write now the noise margin is again rock solid and in fact is now higher at a rate of D/7.0.

 

5. VDSL uptime: 1 days, 14:23:58
6. Data rate: 15828 / 48980
7. Maximum data rate: 14454 / 62377
8. Noise margin: 4.8 / 7.0
9. Line attenuation: 0.0 / 19.1
10. Signal attenuation: 0.0 / 18.8

 

Now I'm thinking that this is what might have caused my speeds to drop since I got my Infinity connection and possibly also on my previous Sky Fibre connection.

Does anyone know what might be happening here and if an engineer visit would help?


Thanks

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2 REPLIES 2
Expert
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Message 2 of 3

Re: Home Hub 5 noise margin stats falling and rising. Possible line fault?

Yeah that is a bit extreme and would indicate a line fault to me. 

 

Stats do raise and lower dependent on time of day and stuff, for example if you sync during the early hours of the morning you can expect a slightly higher sync rate than if you sync at tea time and consrquently you will have your target SNR when you sync which will lower and raise again during the day (mine is around 5.3db at the mo) and the max attainable will go up and down accordingly to (my max attainable is currenlty lower than my sync rate)

 

Expect an SNR varience or around +or- 1db to be normal, 3db drop is a bit extreme and would indicate to me a line fault. I am on a full cabinet which openreach term as "bust" and therefore I should be more succeptable to crosstalk interference which are part of why the SNR goes up and down and mine only drops to around 5db from 6 and thats the worst it drops, quite often it stays around 5.3db

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Aspiring Contributor
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Message 3 of 3

Re: Home Hub 5 noise margin stats falling and rising. Possible line fault?

I thougth the variance was a bit extreme also, and to be in such a short time frame rather than a gradual rise or fall just didn't seem right. I don't know how easy it's going to be to get BT to send Openreach out considering I'm still just about inside the estimated speed they quoted me on signup.

 

 No change in speeds this morning and the HH5 has been up for over 2 days now. I've started logging the stats with  RouterStats 5A, there hasn't been any repeat of yesterdays extreme variance as yet. It will be interesting to see how often this is happening and if there is any pattern in when it happens.

 

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