Bad Modem or lines.

[Comix]

Hi,

After fighting with Afrihost and Telkom for 4 months regarding bad telephone lines, Afrihost have basically told me that I have a faulty modem (Netgear D6300)

I know noise and attenuation does differ from modem to modem however does this mean my modem is possible faulty as Afrihost suggests?

Telkom DuoPlus
US Margin 7
DS Margin 8
DS Line Attenuation 7
US Line Attenuation 3

Netgear D6300
US Margin 8
DS Margin 3
DS Line Attenuation 9
US Line Attenuation 4.4

Belkin N300
US Margin 9
DS Margin 9
DS Line Attenuation 5
US Line Attenuation 2


My house supports VDSL 40Mb, however I'm having sync issues at 20Mb on the Netgear.
The other modems sit just above acceptable noise margins when synced at 20Mb, however are unlikely to support 40Mb.

 

[beesboertjie]

Hi Comix. What does “DS Margin 8” mean? Is it “Downstream Noise Safety Coefficient (SNR) 8 dB”? If your SNR (Signal to Noise Ratio) is in fact only 8 or 3 or 9 dB, then that’s not good.

“If your SNR is below 12dB you are pretty much screwed and will not get a consistent level of ADSL-service. You could try to convince Telkom to rewire the cabling – but this is unlikely to happen.” It says in this article …
https://www.naschenweng.info/2008/10/16/adsl-significance-of-snr-and-attenuation/

Your Downstream Line Attenuation of 7 or 9 or 5 dB means that you’re very close to the exchange (or VDSL box) ... less than 1 km. The length of your copper wire is 507m or 652m or 362m. That’s good, very good.

I’m not an expert. This is just my two cents. I think your modems are fine. The DuoPlus and the Belkin can both handle 300 mbps. And apparently the Netgear can do a whopping 4 giga bit. You only need 40 mbps. I think the problem lies within your copper wire.

 

[TheChamp]

As much as Telkom would like us to think otherwise, providing a good stable 10meg is still a mission for them, let alone 20 to 40megs, I don't think the is anything wrong with your modem, also don't think there is much wrong with your copper pair.

Afrihost is probably clutching at straws, i think your issue is an exchange hardware or software related, Telkom probably know what is the problem. It would be interesting to see how your 'faulty' modem stats would change if you were to drop the speed to 10meg...

 

[Comix]

Hi Comix. What does “DS Margin 8” mean? Is it “Downstream Noise Safety Coefficient (SNR) 8 dB”? If your SNR (Signal to Noise Ratio) is in fact only 8 or 3 or 9 dB, then that’s not good.

Hi beesboertjie, yes those values are in dB.

 

[Comix]

Afrihost is probably clutching at straws, i think your issue is an exchange hardware or software related, Telkom probably know what is the problem. It would be interesting to see how your 'faulty' modem stats would change if you were to drop the speed to 10meg...

Telkom did originally say that it was an underground cable problem, until Afrihost decided it was a Modem/Router fault.
At 10Mb the connection on the Netgear is stable with SnR upload sitting at around 8-12dB.

 

[TheChamp]

Telkom did originally say that it was an underground cable problem, until Afrihost decided it was a Modem/Router fault.
At 10Mb the connection on the Netgear is stable with SnR upload sitting at around 8-12dB.

Underground cable is at times Telkom speak for 'we don't know what the problem is, or we do know but there is nothing we can do to fix it'.

Still think you have a Telkom exchange issue, a faulty modem does not become faulty when you put 20meg through it and regain it's health when the speed is reduced. I think there is an issue that needs to be addressed with the port that your service is connected on, next time you have a tech over ask them to kindly show you the stats with your line disconnected and a modem connected at the exchange.