Luka
144
Thank you both for your precious comments.
t's an apartment, I'm living in the first floor, so the junction box in the apartment is very close to my flat. The cable that first enters to my flat from junction box is hidden/inside walls. Then it distributes the connection to all 5 different sockets in different rooms. They are all functional and sync speeds differ a lot between them. For example the socket in my room which I guess is the farthest gives around 10 Mbit downstream wheras the first socket gives 20 Mbit.
I'm using the first socket closest to the box with 20 meter long RJ11 cable to my modem.
If is there any easy way to disable all other 4 sockets in my house without doing any damage to walls, please let me know. They are not in use.
I also see "faulty installation" notes in demarcation point (box) on cards that main ISP puts to distinguish users/flats. I remember talking to one of the technicians and he telling me that "you have to redo all cabling inside". He was able to get a connection with 30~Mbit of downstream and 10~Mbit of upload directly connecting his device to my line on demarcation point.
@janh I thought SRA was working by looking at fluctuating sync rates. I think my build is from 3-4 days ago. Will update today.
/$ dsl_cpe_pipe.sh lfsg 0
nReturn=0 nDirection=0 bTrellisEnable=1 bBitswapEnable=1 bReTxEnable=0 bVirtualNoiseSupport=0 b20BitSupport=0
/$ dsl_cpe_pipe.sh lfsg 1
nReturn=0 nDirection=1 bTrellisEnable=1 bBitswapEnable=1 bReTxEnable=0 bVirtualNoiseSupport=0 b20BitSupport=0
I'm confused now. Looks like DSLAM doesn't support them...
mpa
145
Most likely, the sockets are connected in daisy-chain style. Open the first socket and disconnect the wires leading to the second.
In case of a star topology, find the distribution point and disconnect all unneeded wires there.
Prefer non-destructive methods over cutting wires, allowing you to reconnect them in the future.
If in doubt, take pictures and ask for help.
You might want to mark the disabled sockets to discourage their use.
At 20 m length, mind the cable quality. Some RJ11 cables may not be ideal for xDSL use.
Perhaps try an ethernet patch cable (Cat 5 or above), with the plugs replaced by RJ11 ones.
If you leave only your socket connected, you might get similar sync speed than with your 20m cable. Are your cables in ductwork? If yes, you should be able to replace them easily.
How the sockets are wired (or have to be wired) depends a lot on where you live, which country are we talking about?
Luka
147
@mpa
I apologize for the late answer. As you have guessed the cables were in dutchwork. I have removed the excess cables. Despite that, I don't see any improvements on my sync rates. But as I see both cables have rotten in the ends of the rj11 output. Would it be any better if I redo them?
This is the box located inside apartment. I wonder if it's possible to make a new connection with new wires? Which approach would be best? I'm afraid that I won't be able to change anything inside the box, just the cables connecting to them.
Cables enter to flat from here.
I have removed the excess cables in every room to make sure and also did that so in the first/closest hole.
You keep using the words "apartment" and "flat". I am guessing you are renting one unit in an apartment building. And that junction box is right outside of your unit, because it doesn't make any sense if it were inside your unit.
No. Do not touch this box, do not touch anything inside, close it and never look at at it again. This box belongs to the building and is maintained exclusively by service technicians. Every pair of wires except the singular one going to your unit is potentially someone else's connection. The only person who can and should work in this distribution box is a service technician hired by a telecom company, if only for the fact that if they screw up, they have to eat the cost of fixing it.
So by this time I hope you own the apartment and don't just rent it. Because if you rent it, you are messing around with other people's property. They will probably not care if an unused wire is missing, but you wouldn't know what they care about.
When you get the advice to "replace cables", what is meant is that you replace a cable going from your router to the outlet on the wall. Not the cabling in the wall. You can do that if you own the place, but not if you rent it.
And, again, you never ever touch the distribution box. There be dragons.
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Actually, I meant the in-wall cables. It is obvious to me that this work can only be done if you a) have the legal right to and b) the necessary skills to do it.
Where I live, these cables are either owned by the telecom provider (and then you can't do anything) or belong to the flat. And here it is relatively common to own the house.
I apologize for not being clear about this and I fully agree with @takimata: close the box and leave it as it is.
My telco provider once fixed corroded contacts, because the sync speed went down to 1MBit. This was free of charge.
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Luka
150
I meant the whole building by saying apartment and meant the part I live in by flat. Sorry for the inconvenience. And obviously I didn't do anything illegal since didn't touch anyone else's cables. It's also our own, not rented. Also, you can legally do whatever you want as long as you don't do any harm to anyone else's connection in the place where I live so don't worry about that. Telecom doesn't own those.
@andyb I rarely get around 1 mbps upstream sync speeds instead of the usual 5.5/6 mbps.
Could you post a screenshot of what @janh's great go-dsl tool (there are ready build downloadable binaries available) shows for your link. Just run the GUI of that tool and save and post a screenshot here...
Alright, so that covers what's inside your unit. But no, you still really, really shouldn't touch that distributor box. Not even telecom technicians dare to touch any wires in there unless they really have to.
Luka
153
@takimata I won't touch the box, and the corroding of the cables I was talking about applies to last picture (RJ 11 outlet).
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This looks considerably nicer than the earlier one (but this is after some wiring changes in your flat, no?)! But this still is quite some attenuation.
And sorry, I had forgotten that you already had posted those (or I would not have reposted the link).
There just isn't much reserves on that link the (CRC) error counters seem okay.
Luka
155
Actually other than FEC and CRC counts I think it looks pretty similar. But no one really used the internet today so that could be the reason. One think I have noticed is upstream CRC counts reach to 5-6k in matter of seconds, then increase very slowly over time like normal, and it's been always like that.
And can you explain what errored seconds and severely errored seconds mean?
Nah, the initial Hlog plot showed clear signs of bridge-taps or more likely superfluously connected sockets to your line and also some odd spikes on the QLN graph, but whether one sees those or not can depend on whether the noise source was active when the QLN data was measured (which is only once per sync period IIRC).
Ah, then they are even less of a problem, if they are mostly transient at the time when DSLAM and modem still need to find the best bitloading...
These are counters of seconds which contain more than a certain threshold of code violations, IIRC SES has higher thresholds than "simple" ES, but the exact numbers and which counters contribute I do not remember...
@Luka The ideal connection would be to have a single cable from the ISP's big box to your modem, without junctions and sockets. Your photos show a lot of junctions between various cables, which was OK for telephone, but not so good for VDSL.
Obviously, you shouldn't mess with ISP's box, so my advice is to run new Cat5e cable, in one piece, from the modem, to the small box where the wires enter your flat. Disconnect old wires, terminate the modem end with RJ11/RJ45 (depending on what your device uses) and connect the other end by twisting the wires - don't solder and don't use clamps.
Or talk to your ISP, they might be able to send a technician to replace that cable if you can convince them the current cable is broken?
Luka
159
I will see what I can do. Unfortunately ISPs here don't really care about such things, you have to hire a technican/electrician yourself from somewhere else. I located the DSLAM box that I'm connected to and it is approximately 1.3 km away, so I think there is nothing much to do regarding sync speeds. I'm just trying to minimize resyncs/errors.
I want to add that it's not really possible to use Mediatek/Econet based chipsets on my line as CRC rockets up to tens of thousands in few hours and the connection just stalls. I've also had BCM63168 based Zyxel modem and it was usable but I was getting resyncs up to 5-6 times per day on some days. I guess Broadcom does that when there is too much CRC for its liking. Still, it was reasonable I guess.
Maybe if only my other end had SRA enabled I wouldn't have this issues... There is FTTH connection available for 5+ years just two streets away but I know that it won't be here soon.
@moeller0 And I genuely want to thank you for all the things you have done and keep doing for the community. Whenever I search something related to CAKE/SQM you are always there providing reliable and important information. 
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hello i couldn't run dsl-gui can anyone help?
