Upstream attenuation

Is there any particular reason why the line attenuation on the upstream has changed?
Connection speed has also dropped from 52 and is currently 44
Speed is around 36 down and 7 up - down can be anything from 26 - 42 up is always around 7
Modem has been disconnected today for around 2 hours but this didn't change the up attenuation when reconnected.
I have a BT Infinity 1 package, installed in July.


11-09-16 DSL Link Downstream Upstream
Connection Speed 52.51 Mbps 8.06 Mbps
Line Attenuation 22.30 dB 23.70 dB
Noise Margin 6.00 dB 6.30 dB

DSL Link Downstream Upstream
16-09-16 Connection Speed 49.00 Mbps 8.07 Mbps
Line Attenuation 22.50 dB 24.10 dB
Noise Margin 7.30 dB 6.90 dB

29-09-16 DSL Link Downstream Upstream
Connection Speed 44.00 Mbps 8.21 Mbps
Line Attenuation 22.20 dB 34.90 dB
Noise Margin 9.90 dB 5.90 dB

10-10-16 DSL Link Downstream Upstream
Connection Speed 44.00 Mbps 7.98 Mbps
Line Attenuation 22.50 dB 34.70 dB
Noise Margin 9.50 dB 6.10 dB

I can't answer your question, but consider readers also need to be aware of your previous thread.

I believe the two threads are closely connected and the information the information in that thread relevant.

It does appear to me from the seemingly fixed 44Mpps and high noise margin that DLM may have applied banding. That doesn't explain what is happening re the attenuation. It is the system trying to cope with whatever is going on.

Edited by RobertoS (Mon 10-Oct-16 18:39:34)

So last time it happened it was fixed by rebooting the router?

If rebooting a modem fixes an odd attenuation figure, then probably a firmware bug in the modem

Yes did seem to fix it when rebooted. But not this time.
I've been using this modem for about 8 months, first with Plusnet then with BT. I did try putting the HH5
On but couldn't find the attenuation information on that hub
Seems that the connection speed has dropped when the attenuation has risen too but maybe that's my imagination. The fibre was only connected at my cabinet in July and I was the first property on it. Might it be crosstalk that has suddenly (seemingly) affected the speed?

Crosstalk increases noise which reduces SNRM, so I don't think it's that. The changing attenuation is more likely to be a line fault or a modem fault.

Attenuation is a measure of signal loss. More signal loss = Less signal, which will give lower speed.

Edited by RobertoS (Tue 11-Oct-16 08:47:41)

I've posted on the Netgear forum to see if anyone knows of a problem.
Will post here if anything comes to light.

Does the HH5 sync at the same upstream speed? That would indicate a line fault.

I've put the HH5 back on - these are the stats:

4. Board version: BT Hub 5A
5. DSL uptime: 0 days, 00:02:06
6. Data rate: 8064 / 42101
7. Maximum data rate: 8064 / 52458
8. Noise margin: 6.0 / 9.6
9. Line attenuation: 34.3 / 22.3
10. Signal attenuation: 35.0 / 20.5