New Smart Hub 2 firmware, big sync improvement

My FTTC connection has synced at around 68Mbps for a long time, and around 18Mbps upload (3dB profile on a Huawei cab). A couple of nights ago the firmware on my Smart Hub 2 was upgraded to v0.24.04.11017-BT, and the sync rates are hugely improved:

https://i.imgur.com/KsWckWE.png

I've gone from getting a pretty consistent 61Mbps down and 17Mbps up on Speedtest.net to 70Mbps down and 19Mbps up. I'm not aware of any changes being made locally that might have improved the condition of this line - I guess it's possible that someone who was causing crosstalk ceased their service recently and that just coincided with the reboot and resync that came with the firmware update, but my understanding of crosstalk was that it was a cumulative thing.

Unfortunately I can only give you information that the SH2 reports, which is limited.

Looking at that and seeing both syncs are capped with high max achievable figures, it is, to me unlikely that what would be a massive jump is due to a firmware update.

Have you been monitoring the line recently to see what the stats were?


Yes, crosstalk is cumulative with every other line contributing something to it - some lines may cause next to nothing and others can cause a lot of noise and the effect very noticable. I have one know interferer that now results in a drop of around 8 Mbps. His line syncs at a full 80 so nothing will get done.


As for your test at 70Mbps - that is still low for a full 80 Mbps sync and 84Mbps achievable. I would be expecting to see it up towards 75 or 76.

I'd been checking the stats page maybe once a week, and the maximum data rate figure had never gone above about 70Mbps. I've always seemed to lose 8-10Mbps of throughput from the sync figure compared to actual download speeds, whether this is something to do with having BT Wifi enabled I am not sure.

Edited by jpm (Thu 07-Jan-21 09:52:39)

It could be a cabinet with Vectoring and they have finally fixed Vectoring issues with the Smart Hub 2 (Vectoring worked but it synced lower than other modems with Vectoring).

The ONLY bit of the firmware that can improve sync is the DSL modem driver/BLOB.
Modem drivers only ever make tiny differences. Vectoring is the only exception where I've seen huge gains from a driver update.

Could be nothing to do with the firmware update though.
It could simply be a crosstalker ceased their service or has been offline.
Something like that is much more likely than such a huge gain from a firmware update.

VDSL2 has so many variables that can affect sync you may never know what caused it.
There certainly aren't lots of users on the BT forums saying their sync has just gone up.

Nothing to do with WiFi - unless someone is logged on and doing a continual 10Mbps traffic stream.

I would still go with Crosstalk or noise and a source disappearing.

8-10 Mbps difference from sync to actual is high and could well still be linked to cross talk taking out or corrupting small amounts of data

The line is 450-500m long so I wouldn't be surprised if there are instances of crosstalk along the length. I'm definitely not complaining at getting 70Mbps of actual throughput.

Edited by jpm (Thu 07-Jan-21 11:40:34)

You will have plenty of cross talk. My line is 450m, and at day 1 when I was possibly the first FTTC customer on the cabinet, my max was up around 90+. Slowly dropped and now around 74 today, although if the noisy neighbour turns his modem off, it will jump to just over 80.