Sudden drop in upstream speed

I've had FTTC for a few weeks now and, up to a few days ago, have been getting around 64Mb/s down and 17Mb/s up. After a few line drops in the early hours I'm now getting 64Mb/s down and only 7 or 8Mb/s up.

I've tested via uploads to a VPS and various speed testers (including BT's). I've tried direct connection of laptop to the openreach modem (using Windows PPPoE), my Billion 7800N in EWAN mode and with a friend's Vigor 2750n. The 2750n reports

Profile State UP Speed Down Speed SNR Upstream SNR Downstream
17a Showtime 8491 (Kbps) 67240 (Kbps) 127 (0.1dB) 64 (0.1dB)

Is there any reason why upstream should suddenly drop from 17 to 7 like this while downstream is unaffected? Is it something that will correct itself over time? I'm pretty sure BT aren't going to want to know as they give no upstream speed guarantees.

Thanks,

Mike

In reply to a post by mzanker:

Is there any reason why upstream should suddenly drop from 17 to 7 like this while downstream is unaffected?

Hello mzanker,

If you can get some more detailed line statistics, they might give you a clearer idea. Perhaps there is frequency-specific line noise that only affects the main upstream band? The Quiet Line Noise (QLN) dataset obtained from a Broadcom-based modem should tell you this. See Paul's ("Baldy_Bird") scripts which can harvest the line statistics automagically. Need more data really. Once upon a time, we had a sudden and baffling drop to 64kbps upstream (yes sixty-four kilobits per second!), and it turned out to be a failed transmit channel in the transceiver. Weirdly, the downstream remained fine!

cheers, a

The graphing scripts can be obtained via the link in the first post in this message:-

Huawei HG612 Modem Graphing Scripts

There is a basic Linux snapshot graphing script along with Windows snapshot AND 24/7 automated monitoring script.

If using the 24/7 logging, be sure to read the setting up instructions to make the whole setting up process just take a few minutes.

Everything needed is now included in the downloadable zip file HG612_wingraphs.zip

Thanks for the replies. Unfortunately it's an ECI Telecom openreach modem, otherwise I'd have had it hacked from day one I really don't have enough time to start playing around inside the ECI one.

Mike

Just wonder if you have had a cap applied ...

an xx/20 service will tend to give around 17Mbps and an xx/10 service can be 7-8 Mbps.

Just a thought.

Thanks to all who replied - this is now resolved. BT claimed that it was a "local access cable fault". In the days following their fix, the upstream speed gradually returned to 17Mb/s.