FTTC - Line Quality - Downstream line rate decreased

[#1]

Hi,

My download speed decreased a few days ago, I was getting 55meg and now I get 40meg.

I have been using the same modem/router (a TT HG635) for years until I tried a new one last October which kept restarting itself so I sent it back after 2 weeks and went back the TT HG635 which has been fine until last week.

I've tried another modem/router which is also showing the same downstream line rate. 

I take screen grabs of my router settings from time to time just in case I need to setup a new one, and I can see the Downstream line rate is now lower:

Line Quality	Now	Previously
Upstream line rate (kbit/s):	14399	12758
Downstream line rate (kbit/s):	46094	62723
Upstream noise safety coefficient (dB):	5.9	6.4
Downstream noise safety coefficient (dB):	6.4	3.3
Upstream interleave depth:	0	0
Downstream interleave depth:	0	0
Line standard:	VDSL	VDSL
Upstream line attenuation (dB):	29.5	30.5
Downstream line attenuation (dB):	14.3	14.6
Upstream output power (dBm):	7.5	7.5
Downstream output power (dBm):	13.3	13.3
Downstream interleave depth:	None	None

It looks like the Downstream noise safety coefficient has increased (almost doubled), I wonder if the very windy conditions have caused an issue? my line to my house is overhead.

I have the Technicolor TG582n and 2 x Openreach modems which I will try, but finding the time between zoom lessons and teams meetings can be difficult.

From Plus.net member centre:

Your broadband service

• Product: Unlimited Fibre Extra
• Estimated Download Range: 36 - 55Mbps
• Estimated Upload Range: 9 - 14Mbps
• Minimum Guaranteed Speed: 31.8Mbps
• Current Line Speed (Download): 62.6Mbps

Thank you

[#2]

It looks like the Downstream noise safety coefficient has increased (almost doubled), I wonder if the very windy conditions have caused an issue? my line to my house is overhead.

Yes, it looks like previously your line was on a 3db Target SNR. The DLM seems to have decided that the line is no longer sufficiently error free to maintain the 3db and has reset to a 6db Target. This will have reduced the maximum attainable speed.

If the errors only increased on a temporary basis then the DLM SHOULD reduce the target back to 3db (eventually!) and your speed should go back up

[#3]

Thank you for the explanation.

I will see how it goes, 40 meg is ok for now. 

I'll check the RJ11 connection (I had replaced the cable back in October) and try with other cables.

Strange how my upstream has increased.

[#4]

I've not had time to check / swap the 'internet cable' yet but it looks like the downstream noise has decreased.

So I think that means DLM has increased the Downstream line rate.

Upstream line rate (kbit/s): 14283
Downstream line rate (kbit/s): 57136
Upstream noise safety coefficient (dB): 5.9
Downstream noise safety coefficient (dB): 5.4