dsl started cutting out frequently a week ago

[Plimogz]

I've been connected in this new place for roughly 2 months now and up to now I'd say that my DSL (or is it adsl) would remain stable for the better part of weeks at a time. But now, since late last week, I'm lucky if the DSL light stays up for a couple of hours at a time.

I thought maybe the modem was overheating, so I opened it up and directed some airflow at the hottest chip on there. It felt like it was helping, but that impression lasted about a day before there was nothing doing anymore. So I got another modem and ditto.

Now, looking into things a bit deeper, it looks like my SNR is bloody terrible with whichever modem I use. It's usually in the 6-7 range so I suppose that's the actual problem.

In between outages I've managed to read online that humidity or other environmental variables can have an impact on signal quality, so maybe I'm experiencing a daily cycle of better/worse signal conditions which I can't quite put my finger on yet. Or maybe neighborhood bandwidth usage has something to do with it. Dunno.

Anyway. I'm looking at some other connection stats and reading up on them and came across this somewhere "Output Power: Indicates how much power each modem is using. You will see power increase as loop length increases. Additionally, sync frequently becomes unstable when output power is > 15-16dB" mine is sitting at 11/13.5 (up/down). What I'm wondering is what kind of loop length are we talking about here? Is this the kind of thing which is counted in miles or in tens or hundreds of yards. Could I see a substantial improvement by splicing into the line right when it gets to my door instead of jacking in at the end of a lengthy, house-girdling run of unknown quality wire?

TL;DR: Has anybody seen substantial improvement in either SNR or Output Power by connecting their DSL modem closer to the phone line's point of entry into their home?

 

[Plimogz]

...and suddenly out of nowhere the thing works fine, but for how long?

Link Information

Uptime: 0 days, 0:15:25
Modulation: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 800 / 6.016
Data Transferred (Sent/Received) [KB/KB]: 0,00 / 0,00
Output Power (Up/Down) [dBm]: 12,5 / 8,5
Line Attenuation (Up/Down) [dB]: 7,5 / 9,0
SN Margin (Up/Down) [dB]: 6,0 / 25,5
Vendor ID (Local/Remote): TMMB / IKNS
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 4 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 5 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0

 

[robmurphy]

Where are you based. If in the UK who provides the DSL service?

Rob.

 

[Plimogz]

Canada, actually.

...and so far today the connection has been good and stable. All the while using my old modem which I had thought was overheating, but in fact doesn't seem to be, given that it's working fine with no active cooling on a day only a few degrees cooler than the hot ones we experienced these last few days.

I'm starting to think that likely as not there's a loose connection near the line's point of entry which is particularly subject to wind/moisture.

Hopefully I can surreptitiously fix this with nothing more than some wire cutters and $5 worth of hardware... Just need to avoid prying eyes and awkward questions from the neighbors.

for the record:


Link Information

Uptime: 0 days, 8:32:37
Modulation: G.992.1 annex A
Bandwidth (Up/Down) [kbps/kbps]: 800 / 6.016
Data Transferred (Sent/Received) [KB/KB]: 0,00 / 0,00
Output Power (Up/Down) [dBm]: 12,5 / 8,5
Line Attenuation (Up/Down) [dB]: 7,5 / 9,0
SN Margin (Up/Down) [dB]: 6,0 / 24,0
Vendor ID (Local/Remote): TMMB / IKNS
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 4 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 5 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 0
HEC Errors (Up/Down): 0 / 0

Although the upstream SNR looks rather iffy.

 

[robmurphy]

The up link SNR is about right. The downlink is very high. It looks like your on ADSL not ADSL2+. Given your low line loss ADSL2+ would give a big increase in downlink (more than 50%), and a good increase in uplink.

Rob

 

[Plimogz]

Oh, is that right? I would suppose that I'm on ADSL, yes. But I didn't realize that these values were about right for that.

So if I'm reading you correctly, these numbers look alright and I'm still no closer to being able to put a finger on what, if anything I can do to possibly stop the intermittent loss of signal?

Though I suppose I was never very close to knowing what exactly is going wrong here. In any case, thanks for the response

 

[ScottMac]

Oh, is that right? I would suppose that I'm on ADSL, yes. But I didn't realize that these values were about right for that.

So if I'm reading you correctly, these numbers look alright and I'm still no closer to being able to put a finger on what, if anything I can do to possibly stop the intermittent loss of signal?

Though I suppose I was never very close to knowing what exactly is going wrong here. In any case, thanks for the response

If it comes back, see if you can associate the return occurrence with some other electrical event. For example, a new CFL bulb in your house, or your neighbor's house (up to a couple away, depending on the serving transformer). Another popular offender are "wall Warts"... the little transformer bricks to feed low-power devices. They can radiate into the power line, or they can transmit the noise like a radio station.

Impulse noise is a killer; you can usually hear the offender with an AM radio tuned between stations. Hold it in front of you such that your body shields one side of the radio and walk around with it.

AM broadcast can also mess up the signal. If the cable feeding your house has a bad shield or bad ground, the signal can make it to the conductors of your DSL signal and screw it up.

You might want to try another DSL filter, cables, and connect power through a filtered power strip (a surge protector).

Also, check all the connections from where the cable connects to your house (at the NID - the grey box on the outside wall to you DSL modem.

If you're really industrious, connect the modem (through a DSL filter) directly to the J11 jack in the NID (eliminates the internal house wiring as the culprit)

 

[robmurphy]

On noisy lines I have had to go up to 18dB. This usualy shows as errors on the line. You may need to check with the DSL provider.

I have connections with 6dB that are stable. They only drop when engineering work is done at night.

Often stability is down to to the line management used (DLM) and the combination of modem and DSLAM (MSAN in the UK). Broadcom chipset modems do appear to have stability problems with UK MSANs from Huawei.

Rob.

 

[Plimogz]

Well, it would appear that I've found the problem:

I had the modem on my desk with all of my computer components strewn about (not currently using a computer case) and the telephone cable (you know the RJ11 one) running from the wall to the modem was laying next to a HDD and across some PSU cables. I'm using a cheap non-twisted cable which is apparently very sensitive to interference and separating everything has resolved the intermittent loss of DSL sync.

It could only be a coincidence, of course, but seeing as how from the moment I moved the modem and cables away from the electronics I've enjoyed days of the same steady connection as I had before, so I'm assuming that this must've been the problem.

Silly me.

Still, many thanks for chiming in and helping me not to look in all the wrong places for my answer.