Power cycling modem improves speed for a few hours

Hi All,

I'm with Be Broadband I've noticed my download speed has been quite slow recently. I've played around with a few settings and found that turning the modem off then back on again sees speeds that I used to get. I recently changed the kit from the Bebox to a Zoom modem with netgear wndr3700 router (long story!).

After restarting the speed stays good for a few hours then eventually drops to the speeds I was getting before.

The stats (connected directly to the modem, cutting out the router) are:

Before restarting are:
SNR down: 27.4
SNR up: 11
Attenuation down: 50
Attenuation up: 28.6
Speed down: 1492
Speed up: 1018

After restarting are:
SNR down: 6.1
SNR up: 6.3
Attenuation down: 47.0
Attenuation up: 28.5
Speed down: 5795
Speed up: 1178

Your SNR (signal to noise radio) is VERY high, restarting the router and it lowering that would mean that either the exchange is raising it due to a noisy/unstable phone line.

Or it could be the router or ADSL filter is faulty.

It could be related to your internal phone wiring but it can be related to a fault on a phone line in your area. I have had to endure the latter constantly recently.

Edited by deleted (Sun 11-Dec-11 22:07:31)

It looks like you have a noisy line. When you restart the router the default target SNR margin is 6dB. Because the line is noisy it can't hold sync at 6dB and the target SNR margin is increased. Each increase will result in a lower sync rate.

If you can try RouterStats to monitor the situation. See http://www.vwlowen.co.uk/internet/files.htm

In reply to a post by Alex1M6:

Your SNR (signal to noise radio) is VERY high, restarting the router and it lowering that would mean that either the exchange is raising it due to a noisy/unstable phone line.

Or it could be the router or ADSL filter is faulty.

It could be related to your internal phone wiring but it can be related to a fault on a phone line in your area. I have had to endure the latter constantly recently.

as BE* don't run any form of DLM the problem could well be the modem-s
or due to noise at the time that sync is established,

As a be* customer i can say that speeds do vary with winter and summer not by a lot but nevertheless they do vary, all the bt line plant is subterranean from exchange to property, and located in the suburbs of a big town,

You could set up your own ping monitor to see if you are getting packet loss issues, which if you are could be an indicator that there is congestion local to you, or could also be interference which you may or may not be able to do something about

Rebooting modem caused you to to be switched from ADSL2+, which it seems you can't hold, to ADSL2 only.

As the Anon poster said 20 minutes ago, it isn't the exchange raising the noise margin.

It is some huge noise event occurring, causing your router to disconnect, then reconnect at the low speed because the noise is still there. The noise margin gets set to 6dB at this point. Then the noise stops so the noise margin goes extremely high.

For more explanation see this page and this one, then the rest of the pages in my Troubleshooting section except Router acting oddly and Odd speed test results.

Make sure you don't get mixed up between the throughput speed you get and the Speed down shown in your stats. Be does seem to be having a few speed problems in some areas at the moment, but I don't think people are getting low connection speeds like you. So theirs is a different issue.

Does the same thing happen with the BeBox? If that is bust, have you any other you can try?

Did this start before Christmas lights started showing up near you? Have you got any new, or replaced any old, electrical or electronic kit, or moved things around?

In reply to a post by XRaySpeX:

Rebooting modem caused you to to be switched from ADSL2+, which it seems you can't hold, to ADSL2 only.

Good spot. Pointing to a definite problem somewhere on this line. You'd expect it to be the other way round!

Great site RobertoS - great explanations of what these terms actually mean.

Your advice has helped me (I think) identify the cause of the problem - we bought a new phone a while ago and it seems that could be the problem. I've swapped it out for the moment and am hoping that it maintains the connection - I did that last night and it was still connecting at a decent speed this morning. I'll get the line stats from the modem tonight just to see.

Thanks for your help, and everyone else. As a complete novice to the telecoms side of the internet it was great to get simple and easy to digest information explaining exactly what the problem was with my stats.

Cheers!