Broadband downstream link speed much lower than Sky shows online

[WestleyZero]

I'm not new to DSL, just want to see if I'm alone in this boat.

Previously with NOW Superfibre . Switched to Sky Superfibre. Sky service activated on Aug 24th. For two weeks straight after Aug 24th the DSL downlink speed has been 70.1 Mpbs every day (i can see the history on https://www.sky.com/servicechecker/broadband/checks) -- no change from what it was with NOW. I expected that as NOW is owned by Sky (even the routers have the exact same interface). I was also aware ISPs monitor the line quality within the first two weeks, and can adjust downlink and uplink speeds.

Then 2 days ago, bang on two weeks from activation, all of a sudden I was disconnected and reconnected at 59 Mpbs. It has not connected higher than that since. I tried reconnecting a few times, in an attempt to try to get the DSLAM to remeasure the line quality and bump up the speed back to 70 Mbps, since the line is definitely capable of more, but no luck.

It feels like Sky capped the speed of the service to 60 Mbps, since it happened right after 2 weeks of activation, and it was sudden.

Has anyone else experienced that?

[cookiemonsteruk]

@WestleyZero 

Could you post your hub stats . That link only leads to our accounts

https://helpforum.sky.com/t5/Broadband/How-to-find-your-Sky-Broadband-router-stats/m-p/2855717#M1014...

[WestleyZero]

Or does anyone here who is more technical know which target SNR/noise margin does Sky use? The drop in downstream link speed (~14.4%) corresponds almost exactly to a 3 dB higher target SNR margin ... but I wouldn't expect Sky to use a different target SNR margin than NOW.

[cookiemonsteruk]

@WestleyZero 

Well. If your cabinet is g.inp enabled it would be 3-6db. If not it would be 6-9db. If you want help please post the required info .

[WestleyZero]

Posting what you asked makes no difference to what I asked, but I included it below to humour you (I wish I saved the ones from 3 days ago as well, before the downlink speed dropped).

Both modems (the old one from NOW and the new one from Sky) now connect at 59 Mbps, so the target SNR in the modem is the same. No works on the cabinet/area/building either (cabinet is close, I can see it from my window, probably less than 100m; number of building phone connections hasnt changed from the looks of the wiring box). Uplink speed has remained the same at 19999 kbps. The symptom of downlink speed dropping all of a sudden, exactly 14 days after activation feels like Sky forcing different parameters - either SNR margin or speed cap. I am curious if anyone else noticed the same symptoms.

These are current. I didn't save the ones from 3 days ago before the speed drop.

[cookiemonsteruk]

@WestleyZero 

Your line attenuation does look like it could perform within 65-80Mbps which may show that you are in or roundabout your guaranteed minimum speed.  Does your line drop during the day ?

[WestleyZero]

No, it didn't fluctuate during the day. I'm aware it can perform higher, as I did state it sync'ed and dl'ed at 70.1 Mpbs for two weeks. 

[cookiemonsteruk]

@WestleyZero 

No poimt humourhng me son. When ya cannae read your ya line stats

[WestleyZero]

Why the snark? I could also claim "no point asking for what was already said, son"

Checked the Sky broadband status page again and it was actually 71.3-71.5 Mbps, before dropping to 59:

Do you know if Sky changes the router's software SNR margin target remotely? I think I still have an old Speedtouch 585 v7 stashed somewhere that I could try to use and manually set the SNR target to 3 dB to see ... the speed difference seems too drastic and sudden to be explained by normal variations or coincidence.

[jamesn123]

@WestleyZero 

Sky cant change the target SNR remotely, its set automatically by Openreach/DLM.

If your speed dropped exactly after the 14 days 'settle in' period I suspect DLM was reset on your line after the 14th day back to 6dB from the 'optimised' 3dB.

Note that its normal for DLM to be reset back to 6dB on a new line provision/migration to another ISP, although it should have happened on the first day of you moving to Sky rather than the end of the training period. 

Your speed should come back on its own after about 10 days of stable connection so I would recommend you leave the Sky hub plugged in and dont keep trying to force a resync as this will cause DLM to reset the 'stable connection' time period. 

[WestleyZero]

Yes, that's what I suspected above too. However, it's not entirely true that they can't set it remotely. There are two settings for target snr margin, one on the dslam side and one in the modem. The latter can be adjusted in some models that permit it (some even have a GUI option for it). https://www.increasebroadbandspeed.co.uk/tip7

Sky already has control remotely on some things on this modern of theirs, e.g. they can read the state of the local wifi or firmware, so theoretically could also adjust other parameters.

The fact they dropped it to 6db after 2 weeks of stable 71+ Mbps suggests it's not going to get back up on its own. Each ISP uses different defaults, sadly (see above article for some values). At EE I had even higher speeds, close to 76 Mbps.

If it's the client side target snr margin that dropped following remote instruction from sky then I can try my older Speedtouch modem which allows changing the target snr margin. But if it's the dslam value then there's nothing I can do, as it's always the greater of the two.

Indeed I'm aware about reconnecting too many times, but as far as I recall, the threshold for resetting line quality was once every 30 minutes, as in if it's more rare than that then the dslam shouldn't reset the line quality monitoring. 

[jamesn123]

@WestleyZero 

That article is for ADSL not VDSL. Sky do not control the SNR, its done on the Openreach kit side. Modems that allow you to adjust it only give you options to improve stability by tweaking it the other way, the maximum speed setting will always be dictated by DLM. 

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@WestleyZero wrote:

The fact they dropped it to 6db after 2 weeks of stable 71+ Mbps suggests it's not going to get back up on its own.

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Thats not strictly the case. Like I said its normal for a profile to be reset (By DSLAM not Sky) on a new provision so you just need to be patient. 

[WestleyZero]

I meant it would have been expected to set it at 6db from the getgo, not after the 14 weeks, if it's their default. If they upped the margin after measuring the line for 2 weeks, then that usually means the new value is a look-up value corresponding to what they measured, hence why I said I'm not holding my breath that speed will climb later. You're right that it's possible, but in my experience unlikely.

In the past, SSE, EE, Vodafone - all were already in the correct ballpark within 2 weeks.

I am still within the 30 days cooloff period ... if I wait to get lucky and I don't then I'm stuck for 18 months.

Appreciate the reply nonetheless, though.

[WestleyZero]

Well, I  have been patient ... it's been 1 month and 2 weeks. Speed is exactly the same, 59 Mbps. 

[WestleyZero]

Actually, it dropped to 58.2 Mbps. Fantastic. Well done, Sky!

Is there any point of asking Sky to look into it or will I just be told the old adage "it's above the minimum guaranteed speed, **** off" ?