cancel
Showing results for 
Search instead for 
Did you mean: 

Poor sync speeds. Any suggestions?

PeteSmith
Dabbler
Posts: 11
Registered: 29-12-2015

Poor sync speeds. Any suggestions?

Hi.
I've recently noticed I've got "poor" (relatively speaking!) sync rates.
We had FTTC installed ~ April this year. There was a problem with water in the junction hole outside the house, so they propped the enclosure up on bricks(!) to keep it out of the puddle in there.
The Openreach engineer tested the system with his portable tester, and showed a full 80/20 down/up sync. We're only ~300m from the FTTC cabinet.
Once the HG612 was installed,  results from a broadband speed tester showed 78Mbit/15Mbit. I was a little disappointed with the upload, but I don't do any uploading, so it's not a big deal for me. When updating games through Steam, I've actually seen ~8Mbyte transfer rates.
I've been doing a spot of decorating in the hall, and wanted to move all of the modem/router boxes round, as the hall wall was covered in cables, beige boxes and wall-warts. Plus the siting for the wireless router wasn't optimal, as it was against a block wall.
When we had the house re-wired, we had Cat5E fitted throughout, so I piggybacked an unused pair from the phone extension that was put in (appears inside the , and interrupted the phone extension and extracted that pair at a more accessible location.
Before I put the floor down, I wanted to check the new extension wiring was OK, so I punched down the pair to the DSL extension IDC header in my Mk3 faceplate, crimped an FCC68 4/4 with the same pair on the centre 2 pins on the a cable, and joined the two with a Cat5E IDC punch-down connector joint, connected it up, and was disappointed to see my download speed was ~40Mbit. Upload was still 15.
I figured it was my extension, so put the old Cat3 VDSL modem lead into the Mk3 faceplate & modem, re-started, and got 40Mbit. I then thought it was because I'd left the new extension in, so the VDSL was "Teed". I levered it out, and still got 40Mbit.
All the other work I've done on my other cables, when tested with a Fluke cable tester, shows them all capable of 1000base TX (but not quite Cat6). I couldn't test this cable in the same way, but the speed actually *improves* when I connect the modem via the extension compared to the standard lead.
To allow me to do some more testing, I've unlocked my HG612 (3rd gen IIRC - it's got a 3 on the label on the back). This confirms that the max attainable rate is ~ 40M up and 15M down.
I've run the HG612 stats tool, and attached the details to this post.
The trouble is, I'm not 100% sure what I'm looking for. As an electronic engineer, none of the figures look "bad" in that there's no huge step discontinuity in any of the figures.
One thing I have seen is that I've seen someone elses post with "This is what mine looks like", and the *shape* is the same, but the bits per tone are doubled, e.g. their image showed 12 bits/tone in the places mine's showing 6 bits/tone.
This post http://community.plus.net/forum/index.php/topic,147016.msg1294252.html#msg1294252 shows "poor upload" with 6 bit/tone, but download with 15>12
This one http://community.plus.net/forum/index.php/topic,147016.msg1294323.html#msg1294323 shows a shape like mine, but more bits/tone.
I'm 99% sure that it's not in my wiring, as if I connect the BT faceplate with the BT lead to the BT modem, it reports the sync speed is commensurate with the download speeds I'm seeing. I'm not even using the router at this point - this is a Cat5E cable going straight into the modem.
I've raised this as a ticket, and I've been asked to provide 3 appropriate times for a BT engineer to visit, but it's got the usual warning of "if it's in your wiring, that'll be £50 please".
As usual, *for me*, plusnet have been great. I got in touch, they confirmed no known issues on my exchange, raised a fault, and got back to me. This isn't a moan at Plusnet! I just want to make sure I've covered all bases.
If it's a fault with the faceplate or router, is this classed as "my problem" or not? Are BT likely to be arsey as I've re-flashed the firmware on the HG612? I hope I've kept the old firmware image, as https://huaweihg612hacking.wordpress.com/ have gone awol :-(
Is there anything else that someone can suggest I try? e.g.

  • Leaving the modem turned off overnight
    Jumping up and down and shouting & crying
    Holding my breath until my face turns blue?



I'm always open to suggestions!
FWIW, if it turns out there's a terminal issue with the line, I'm happy to save ~£4 a month and drop down to a 40Mbit service. I'd rather have the 80 though!
Thanks.
Pete.
8 REPLIES
PeteSmith
Dabbler
Posts: 11
Registered: 29-12-2015

Re: Poor sync speeds. Any suggestions?

Replying to my own post here!
Done some more investigation, and I think poor SNR may be the problem.
Theres a page on Kits which describes the relationship between SNR and bits per tone.
The "perfect" SNR of 50dB would give 15bits/tone.
Mine is down to 30db at best. Every 3db drop will reduce the bits per tone by 1. This tallies with mine being 6 bits down.
So - is poor SNR likely to be a street cab/ BT wiring issue, or something that's my problem?
Thanks.
Pete.
PeteSmith
Dabbler
Posts: 11
Registered: 29-12-2015

Re: Poor sync speeds. Any suggestions?

Replying to myself once again!  Cheesy
I've checked the history of the ticket on Plusnet. Seems I don't get an email reply when the ticket is update for internal reasons.
The report that BT supplied to Plusnet shows...
[tt]Radio Frequency Ingress Detected
Cross Talk             Detected[/tt]
So I'm guessing there *is* a definite fault somewhere. Just hope it's nothing I've done!
Pete.
Plusnet Help Team
Plusnet Help Team
Posts: 13,487
Thanks: 248
Fixes: 68
Registered: 27-04-2007

Re: Poor sync speeds. Any suggestions?

Hi Pete,
I'd look at the state of the SNR as a symptom rather than the issue itself.
I can see from ticket 116591728 that an engineer visit is needed as the next step so I'm booking that now for you.
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
PeteSmith
Dabbler
Posts: 11
Registered: 29-12-2015

Re: Poor sync speeds. Any suggestions?

Hi.
Thanks. Engineer's booked for Friday.
Just hope it's not been caused by a repeat of the last problem we had - BT Openreach guy rummaging round inside the junction box on the pavement outside my house *with a crowbar*  Undecided
I also appreciate SNR issues are an effect not a cause. I just hope I'm not the cause!
Pete.
Plusnet Help Team
Plusnet Help Team
Posts: 13,487
Thanks: 248
Fixes: 68
Registered: 27-04-2007

Re: Poor sync speeds. Any suggestions?

I've set a reminder to check in on this on Friday for you.
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
PeteSmith
Dabbler
Posts: 11
Registered: 29-12-2015

Re: Poor sync speeds. Any suggestions?

The engineer came round today.
There were 2 issues: Weak cable in the master socket - he tried to pull the jelly bean joint out, and the whole thing snapped off!
Once 2 more vans came round, and they'd stripped enough armoured cable off to get to the pair, they extended it, and were able to put their TDR tester on it.
This then highlighted the real issue : a short circuit on one of the wires to an adjacent circuit, somewhere under the road/pavement.
They're sending out someone with a mini-digger next week!
Pete.
Plusnet Help Team
Plusnet Help Team
Posts: 13,487
Thanks: 248
Fixes: 68
Registered: 27-04-2007

Re: Poor sync speeds. Any suggestions?

Cheers Pete,
Please reply back if there's any issues next week or if you have any questions in the meantime.
If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
PeteSmith
Dabbler
Posts: 11
Registered: 29-12-2015

Re: Poor sync speeds. Any suggestions?

Looks like we're getting somewhere.
Engineer who turned up last Friday wasn't as good as the one who turned up today.
There was a mix up with BT, who sent the "Underground" engineer out on Monday who did something, said "Nothing wrong here", and closed the case.
This means another one turned up today.
He checked what the last one had found, and figured out the "battery contact" 289m away was actually the DSLAM in the street cabinet.
There was no sign of any issues other than REIN. Cable was 61R impedance, with >>100MR between the pairs and earth, and 0v between any one pair and earth, which ruled out battery contact.
He then called one of the underground people, and found that the cable outside the house (about 10 feet of it) was dodgy.
He patched in an unused pair (I assume) and the sync went from 40/15 up to 65/24 (attainable).
I've run another set of tests on the router, and the SNR is greatly improved, having gone from 30db (max) to 45db+ (max).
The bits/tone is still low in tones 250-750 (matching the old shape), but I'm hoping that the DLM will settle all of this out over the next 3 weeks, and I'll start to get better performance.
Even if not, 35 to 56 is a good improvement.
Pete.