Snr drops from 26 to -7. How can i know if its my home cable or ISP?

rocman3

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Jan 2, 2014
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My ISP doesn't understand this problem so i need help. The reason for that is this problem appears randomly. For example i can use my network without a drop at 26-27 snr for 6-7 days. But suddenly my snr drops? And my network lose connection. So when ISP guy came to my home they can't see anything wrong and blame my cable system. Can you see a detail that will show the source of this problem?

I mean this problems occurs only for a minute then it returns to normal. So ISP guy waits for 10 minutes then says everything is okay..

Other info:

- Sometimes Upstream snr drops to 1 or 2. And it continues to stay like that for few minutes if i don't reset my modem.

- Mostly its Downstream snr that drops to -6 or -7 suddenly and makes my network lose connection. Then it returns to its initial value of 26.

- But sometimes it doesn't return to 26 and instead stay at a random value between 2 to 10. And my network speed will be reduced.

- My Line Attenuation is 20(U) to 30(D). And it is always at that value but once in a hundred drops i see it increases to 40 to 50. But this happens so rarely, last time i saw that was like a month ago and my network lose connections everyday.

- ISP guy came to my house and checked modem and splitter they don't have any fault. So it is either the cable in the house or from ISP side.

- Once i saw that my Up snr hit +140 or something for a few seconds or a minute.

- Now i need to prove that the fault is from ISP or else i need to pay some money to reinstall my home cable. Which might help and might not.

Anyone can help me?
 
I suspect I misunderstood. I am going to bet you have a DSL connection. Many dsl modems do not display things like SNR ratio so most times people asking are talking cable modems. From what I can tell your numbers when things work well are very good.

Telephone wire to a point is easier since it is thinner and more flexible than coax. There should be a box with a rj11 jack inside your house...although some people it is outside...that your internal wires all connect to. You want to plug in at that point to test. This is what the phone company calls their demark. They are responsible to that box so if it has issues plugged directly in then it is their problem.

It is highly unlikely the wires in your house are causing random outages. Most times it is always bad when it is in house wires. There are a lot of splices in telephone wire between you and the telephone office any one of these that is loose or has moister in it can cause issues.
 
What you may want to try is running a cable over the floor to the point the cable enters your house just to test. This will show if the problem is your in house wires or not.

It depends on what exact type of docsis you are running as to what the values should be. 26 is a very low number for most modern cable modems. If it says you are using 64qam then you are ok. If it is using 256qam the recommended minimum is between 30 and 33. Many people get in the low 40's.
 

USAFRet

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I had this exact thing (but worse) happen several years ago.
Cox cable, internet would go out completely. 2, 3, 4 times a week. It would come back sometime in the wee hours.

Call them...guy comes out the next day, all is good. That evening, it dies again.
So I started monitoring the readings on the incoming side of the modem. Voltage and SNR.
And keeping a log of when it died and what the readings were at that time. Excel chart, all that jazz.

This went on for 3-4 months.
Everything from the street junction box to my screen was replaced.
Eventually I got to the point where I could tell to within 10-15 minutes as to when it would actually die.
Called the tech line one evening, blah, blah..."Check my account history" 'Whoa...that a lot of stuff'
[me] "OK, wait for it.....monitor the signal coming to my house....wait for it, wait for it....DIED"
[him] "Um, wow! OK..."

The next day, I had 3 Cox trucks and a supervisor at my house.

Turned out, it was an upstream box dying due to temp and humidity.
 

rocman3

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Jan 2, 2014
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Well 26 snr is wheni have 4mb speed. When i get 8mb (which is maximum here) my snr drops to 17. But i always thought snr isn't bad. As far as i know if snr drops below 10 my connection might have drops. So i never thought this was the problem.



Then i will get a new cable. I didn't want to do this because i don't know how i will manage to run a new cable from outside to inside. :D But thats my only option i guess.
 

USAFRet

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No, I meant at the point where it comes in through the wall, on the inside.
Not from outside to inside.
 
I suspect I misunderstood. I am going to bet you have a DSL connection. Many dsl modems do not display things like SNR ratio so most times people asking are talking cable modems. From what I can tell your numbers when things work well are very good.

Telephone wire to a point is easier since it is thinner and more flexible than coax. There should be a box with a rj11 jack inside your house...although some people it is outside...that your internal wires all connect to. You want to plug in at that point to test. This is what the phone company calls their demark. They are responsible to that box so if it has issues plugged directly in then it is their problem.

It is highly unlikely the wires in your house are causing random outages. Most times it is always bad when it is in house wires. There are a lot of splices in telephone wire between you and the telephone office any one of these that is loose or has moister in it can cause issues.
 

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