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Previously I had an SNR Margin of 18db and since two days ago, it has dropped significantly, from 18 to around 9~12db!
I had an issue with the specified speed, and called my ISP, they checked my line and it was OK, then they said, we need to check the center.
After that I noticed my SNR Margin has dropped significantly!
Before: enter image description here

After: enter image description here

The CRC has also increased significantly compared to before which IMHO means there are many requests failing because of either noise or something else caused by this.

I need to say this as well, on 12Mb, this is how my connection stats looked like : enter image description here

Backstory :

My issue with ISP was I couldn't achieve the specified speed. It used to be fine but then lately I noticed my 16Mb connection, cant even download more than 1.2~1.3MB/s! meaning the speed was actually around 9~10Mbs. In my 8Mb, I could only achieve 500KB~920KB/s which was not OK, I had to get constantly 1MB/s or around that number. In order to fix this temporarily they set my 8Mb connection to 12Mb and that's the screenshot you see above. After 3 weeks of going back and forth they finally came and checked my Line, my line was OK, and they said they need to check their equipment and this happened. now my like is struggling with the 8Mb connection!

update this is the speedtest.net results I just got!:

enter image description here enter image description here

I need to know what could have caused this so I can talk to the ISP agents prepared, they have the tendency to deceive people if they know the other person has little/no knowledge concerning the matter at hand.

Hossein
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  • I already asked this on [networkengineering][6], since I think it belongs there, but it was closed as offTopic, so I asked this here. so if it doesnt fit here, please kindly move it to the appropriate section – Hossein Feb 21 '19 at 09:57
  • "since two days ago", how much rain have you had since it was working ok? I would be looking at inside wiring as opposed to the ISP. It's not impossible for a bad pair on the local loop to the DSLAM, but much more likely it's between the dsl modem and the Demarcation point. – Tim_Stewart Feb 21 '19 at 15:42
  • Actually there was rain two days ago, but the same day, an ISP representative/technician came and checked the whole wiring and it was OK. it only happened after that. I'm sure the line OK because its well protected and also the line attenuation hasn't changed. They checked the modem as well, tried another modem of theirs, and said the modem was OK as well. thats why I'm asking to know other possibilities that are not on my part. – Hossein Feb 21 '19 at 18:31
  • The technicians responsibility is from the pole/underground to the Demarcation point, not your inside wiring. What did he tell you the decibel loss was from the dmarc to the modem? If he/she did not give you this, he/she didn't test it... I'm guessing if this happened after rain, then water is getting in somewhere, possibly the outside box (demarc). – Tim_Stewart Feb 21 '19 at 19:26
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    *"they finally came and checked my Line, my line was OK"* -- There are many possible ways to test your loop. See [Testing Copper Cabling the Right Way](https://www.ecmweb.com/content/testing-copper-cabling-right-way). In my experience, you need a properly-trained tech to perform a TDR test to resolve noise issues on ADSL. See my comments to https://superuser.com/questions/1253210/can-a-cheap-adsl-modem-router-be-responsible-for-frequent-disconnects-from-and-s *"I'm sure the line OK because ... the line attenuation hasn't changed."* -- Faulty reasoning. – sawdust Feb 21 '19 at 23:05
  • @Tim_Stewart: Thanks a lot. no it was raining that day as well. he both tested the internal wiring by testing his modem/equipment inside the house, then went out, and connected the modem to the line where it enters the house (from the demarcation box( the box where each telephone line, goes to a house in our block)) . And since nothing changed, including line attenuation, he said everything with your line is fine. We had rain for the past two weeks, and its not like it only rained in that specific time). thats why I'm saying I'm very sure its not rain. – Hossein Feb 22 '19 at 02:52
  • @sawdust: Thanks a lot. I'm looking at it now :) – Hossein Feb 22 '19 at 02:52

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Simple short answer SNR is Signal + Noise your internet was 8mb and now it's 12mb every time you upgrade your internet speed you will lose Signal strength

Code of War
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