cancel
Showing results for 
Search instead for 
Did you mean: 

Fluctuating connection speeds

N/A

Fluctuating connection speeds

I've been chasing my tail with Plus.net on this for an absurd amount of time now so I thought I'd try and see if anyone here has any useful insights which might help me out:

Ever since Plus.net put me on to MaxDSL I've noticed that my router has been reporting wildly fluctuating down stream connection speeds (this may've been happening beforehand as well as it's not something that I'd ever paid much attention to). These are generally between 2000kbps and 3500kbps but every now and then a 768kpbs or a 480kpbs sneaks in which keeps my stable rate down at a 500kpbs. Upstream speed is a rock solid 448kpbs.

I've had a BT engineer out and while he failed to find any faults (I was connecting at around 3000kbps for a couple of hours that day) he did replace my microfilters with a new ADSL faceplate. This seemed to stablise my down stream connection speeds (I get the low speeds less often but not less often enough) but ultimately hasn't really helped.

I'm using a Netgear DG834GT router though I have tried an ADSL USB modem (with no obvious change in speed).

Any clues or suggestions which might help me get get even a wee bit further forward would be greatly appreciated as I don't think I can justify paying £25 a month for a 0.5Mbps connection for very much longer.
19 REPLIES
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Fluctuating connection speeds

Do you know what SNR figures you've been getting relative to the synch rate figures while these problems have been apparent? To get the full picture you need to know both synch rate and SNR
N/A

Fluctuating connection speeds

I haven't been watching my SNR figures. However, some quick experimentation this morning (watching the SNR for 10 minutes and then rebooting) produced the following:

Sync: 1000kbps
SNR: 20 - 27db

Reboot

Sync: 3400
SNR: 14.8 - 15.5

Reboot

Sync: 1700
SNR: 24.8 - 25.5

Reboot

Sync: 3300
SNR: 12.1 - 17.7

Router lost connection/reconnected

Sync: 896
SNR: 15.8 - 27.6

Downstream SNR is always exactly 20.0db.

I don't know how the SNR should behave (a quick check on the web suggests the values are reasonable) but I'm surprised that rebooting the router has such an effect.

I'm unsure what to make of all of that (if anything).
N/A

Fluctuating connection speeds

Check to see if the BT engineer only connected to terminals 2 and 5 on the replacement faceplate. If he also connected to terminals 3 and 4 remove these wire. If you have not seen this discussed on this forum before just do a search for 'ring wire' and you will see many threads.

The SNR will be lower for higher sync speeds and I normally see short disconnecions, 30 seconds, when it drop to around 12db
N/A

Fluctuating connection speeds

I have the Netgear router, where is this SNR everyone mentions? I have readings for Line Attenuation 54db - 31.5db
and Noise Margin 4db - 17db
Upstream never moves from 448 down stream is 6144 but sometime drops to 5k
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Fluctuating connection speeds

What your router calls "Noise Margin" is the same as SNR (Signal to Noise Ratio)
N/A

Fluctuating connection speeds

Thanks, are my figures ok?
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Fluctuating connection speeds

Quote
I don't know how the SNR should behave (a quick check on the web suggests the values are reasonable) but I'm surprised that rebooting the router has such an effect.


Normally if you are watching the SNR when your router is synched at a particular rate I would not expect it to change by more than 1-2 dB. If it fluctuates wildly by several dB it would indicate that there is something wrong either with your modem or home phone wiring or the BT link between you and the exchange.

You can eliminate the effect of your home phone wiring by plugging your router/modem straight into the test socket (if you have one) behind the face plate of the Bt master socket

Synch rate is related to SNR in that SNR decreases by about 6-7dB for a doubling of synch rate
N/A

Fluctuating connection speeds

Thanks.
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Fluctuating connection speeds

@noelwilde

Looks OK to me-- 4dB is a bit close to the bone but allegedly Netgears can work closer to 0dB than most routers (maybe they lie about their SNR readings Tongue )
N/A

Fluctuating connection speeds

I've just looked at the faceplate the BT engineer installed and only terminals 2 and 5 are connected. For a couple of weeks I was using the test socket directly and seeing the same kind of sync behaviour so I would've been surprised (but probably not shocked) had something like that made a difference.

From what shellsong is saying it would appear that the SNR variations I'm seeing aren't what I'd want to see. It seems curious to me that the SNR is more stable the higher the synch rate is (anything over 3200 seems to have an SNR that varies by no more than 0.2db for the most part (though just as I'm typing this it has collapsed from 15.1db to 4.9db on a synch rate of 3328 and disconnected) whereas under 1000kbps the SNR can vary by as much as 15db) is there anything that can be deduced from that?

I think I'll try and play around with having the router plugged into the test socket and see what the SNR does then.

Thanks for the ideas.
N/A

Fluctuating connection speeds

Connecting directly to the test socket does nothing to change the behaviour of the SNR - it still swings about as before.

I've noticed that I can connect at between 2600 at 3300kbps with SNR between 14 and 17 for some time then suddenly the SNR will collapse right down to 8 and below (causing a resync). What could possibly cause that (I've seen this behaviour both when connected to the test socket and when connected normally).

I've added this information to my outstanding ticket but I'm at a dead end again. Does anyone have any idea if there's anything else I can try to get to the bottom of this. (It's got to the point where I've started thinking about abandoning phone lines altogther and getting a cable connection instead!).
shellsong
Grafter
Posts: 2,191
Registered: 03-08-2007

Fluctuating connection speeds

Does the main variation of SNR tend to occur during a particular part of the day? The evening peak period usually is the time that most problems occur partly because most sources of electrical interference are apparent then and partly because greater ADSL traffic in the phone wires bundled together between you and the exchange can sometimes introduce more noise in the form of crosstalk
N/A

Re: Fluctuating connection speeds

Quote
I've been chasing my tail with Plus.net on this for an absurd amount of time now so I thought I'd try and see if anyone here has any useful insights which might help me out:

Ever since Plus.net put me on to MaxDSL I've noticed that my router has been reporting wildly fluctuating down stream connection speeds (this may've been happening beforehand as well as it's not something that I'd ever paid much attention to). These are generally between 2000kbps and 3500kbps but every now and then a 768kpbs or a 480kpbs sneaks in which keeps my stable rate down at a 500kpbs. Upstream speed is a rock solid 448kpbs.

I've had a BT engineer out and while he failed to find any faults (I was connecting at around 3000kbps for a couple of hours that day) he did replace my microfilters with a new ADSL faceplate. This seemed to stablise my down stream connection speeds (I get the low speeds less often but not less often enough) but ultimately hasn't really helped.

I'm using a Netgear DG834GT router though I have tried an ADSL USB modem (with no obvious change in speed).

Any clues or suggestions which might help me get get even a wee bit further forward would be greatly appreciated as I don't think I can justify paying £25 a month for a 0.5Mbps connection for very much longer.


thebrown, don't listen to any nonsense about testing line. Fact is, I have the same problem as you, mine goes down to around 760kbs during the morning to afternoon. It's happened now for 4 or 5 days.
I'm sick of people suggesting 'try this' and 'try that'.
It's a falut with PN or BT or whoever. If you look around the broadband help section, you'll that LOTS of people are suddenly getting this. You shouldn't be suckered into thinking it's a problem on your line. Fact is, I had a superb CONSISTANT 5-6mb connection speed for 3 months+ 24/7 up until 4-5 day ago. Now, I suddenly get between 760kbs-3mb. And there seems to be a patern forming for when I get certain shoddy speeds.
PlusNet NEEDS to sort this sorry mess out and explain to us what's going on exactly.
Alecto
Grafter
Posts: 2,886
Registered: 30-07-2007

Fluctuating connection speeds

Provided your l ine is not dropping connection frequently, a varying SNR is nothing to be too concerned about.

Mine for example starts at 6dB in a morning, but in the evening often reduces to zero, or a negative/unmeasurable figure (denoted by a very large figure indeed on the Netgear stats). Sometimes it resyncs at a lower rate, but not often, and even then it does not always affect my stable rate.

I gather it is more common for SNR to reduce in the evening - presumably something to do with everything being busier - but unless your connection is dropping I wouldn't worry too much.