Any Cable Modem Gurus? Insane Quantity of Correctable Errors

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LoneRanger

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We moved to a new address in the same zipcode and simply transferred our internet service from the old address, new address being already wired for our cable broadband ISP's service (prev owners had same ISP). At our old address we would only see a handful of correctable errors. At the new (to us) house however, the Zoom 5370 cable modem (docsis 3.0) has accumulated over 3 million correctables in only two days of up time.

Speed tests show that performance is right at what we pay for, 30Mbps down 5 Mbps up. Latency, or ping is coming up between 31 - 44 ms with various broadband speed tests. Also note the rather high downstream power levels. Ideas as to cause? At the former house, I would see a total of < 1000 correctables over an entire month of up time and downstream power in the 3 - 4 dBmV range

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Originally Posted by JohnnyJohnson
Did you give your ISP the MAC address of your modem?


Yes, they sent a tech out to enable the transfer of service, that was last Saturday. He said the MAC id was already on our account since same modem we had at former house where the acct was transferring from. Plus, he read the MAC id to a guy on the phone at the head end or wherever, to confirm it matched.
 
Your downstream power levels are kind of high, ideally you want them at 0 though -10 to +10 is acceptable, while your upstream is kind of low, these should be +40 to +52.

You may have an issue with your drop. I had random reboots and tons of uncorrectable errors, turns out a squirrel or something chewed the coax up at the pole.
 
That would appear to my amateur eyes to be some sort of line or splitter issue.(well both are line issues but you get the idea)

Does the line come right in and only go to the cable modem? is there a crusty 5way splitter on the outside of house?
what kind of coax is used? 10 year old line from pole?

Usually this type of issue is either an splitter or line issue due to age/water/animals.
 
Your downstream power levels are whacked, you should call your ISP and have then send someone out to test the line. Something is def not right - your connectivity is borderline. I'm surprised your SNR is that good with the power levels that messed up. They should be close to 0.

Upstream is a bit low as well, but within acceptable range.

But your downstream is a mess.

I had similar issues at my house a couple years ago. Spectrum was actually great and re-wired everything at no cost. Now I have 1 splitter and around -2 power and over 40 snr. My power was hovering around -12 when I was having problems.

All my other TVs use a roku with the spectrum app now.
 
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Yup try to eliminate the number of splitters between your modem and your primary incoming line, and use fresh Coaxial cable if you can.

If that doesn't work, a tech can come out and check signals at the nearby distribution box and also verify that the drop (the line between the distribution box and your home) is OK. When the tech comes out, ask them to go over your wiring to the modem and they'll maybe install some fresh/better splitters.

You can refer to my previous thread here where I have a diagram of my current wiring setup which has been pretty ideal for me.

https://www.bobistheoilguy.com/foru...e-there-any-cable-techs-here#Post4873014
 
Check for any non-compression cable fittings on all the coax you can get to. Check for any cheap splitters or taps. Have the cable company come out and check their drop to the demarcation point(usually on the side of the house). Newer cable services using DOCSIS 3.0, MoCA for whole-home DVR(and the slave boxes for Comcast's Xfinity X1 platform do use MoCA to communicate with the main box via IP) do need clean signal to work. Years ago, the cable companies were able to get away with shoddy wiring, until cable systems had to do some FCC-mandated rebanding and the two major systems(Comcast/Time Warner) started to reclaim analog channels to digital in order to support DOCSIS 3.0, switched digital TV and more HD channels on the video side.
 
I will add my parents had some weird internet issues 20 years ago - their TVs had signal but the cable modem would drop intermittently. Comcast sent a tech and it was a bad 25 year old drop that got breached with a root. They sent their construction team out, dug up a section of driveway and replaced the bad buried conduit and coax cable with new stuff.
 
When we had trouble with our cable modem a few years ago it was the 3rd tech that figured out that the signal was too strong and lowered it down with an inline connector (was older infrastructure where we are, since upgraded). He said that a lot of tech's think that the stronger the better when it should actually be kept in a healthy range.
 
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Lots of people splice into their home's coaxial cable with twist-on or crimp-on F-connectors. And those are simply not good for RF losses/attenuation. The compression-type ones are the best, and the tools to strip and terminate RG-6/RG-59 aren't that terrible pricewise. Compression fittings combined with the foil shield and wire braid in coaxial cable form the main RF shielding that keeps the RF in a coax system from causing weird things to happen.

Ideal now makes a push-on F-connector that needs no tools and it seems to work decently well. Not a substitute for the Thomas & Betts or Commscope ones the cable company uses but they are good in a pinch.
 
Originally Posted by Skippy722
Your downstream power levels are kind of high, ideally you want them at 0 though -10 to +10 is acceptable, while your upstream is kind of low, these should be +40 to +52.

You may have an issue with your drop. I had random reboots and tons of uncorrectable errors, turns out a squirrel or something chewed the coax up at the pole.

Agree. I have been told downstream power of +7/-7 is what modems like to see.
 
I just found out this morning that the previous owner had problems with the connection and the broadband provider (Wide Open West) came out and ran a new cable drop last year from the yard box (easement) to the house box (demarcation point). So I would not expect a problem with the cable between those two points.

Don't like the prospect but I'm going to need to go in the crawl space and inspect for any installed splitters, or other line interruptions. And maybe a peek inside the box at the demarcation point on the house. I still have quite a few 75 ohm type F terminator caps to cap off all open sockets in the house, and there appear to be a bunch, so I'll add that task to the crawl space safari I'm planning.

I guess what's so annoying about it is, my former house was perfect in this regard. My downstream power was always between +1 to +4 and only hit 4 during real cold snaps in the winter (single digit temps), my snr's where 39 - 41 down and 41 - 44 up, and very few errors maybe a hundred or so for 30 days of up time. Then you move to a different place and bam, time to troubleshoot a cable plant again.
 
With modern testers it can tell them if the line itself is a problem and how far long or if it's a problem from a device on the line. Also if it's a problem from the street.

I'd have them come out and diagnose it. You will end up with a better connection that way.
 
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Another thought: sometimes the techs will throw a splitter on to attenuate the downstream signal, which has the side affect of boosting the upstream. If you find a splitter or 2, make sure to double check your power levels, as they may shoot way up.

The signal coming into my house is really hot, like +15. Tech put a splitter with a -7 rating on the line, keeps my power levels between +5 and +9 on average. Probably the "easy" or "lazy" way to do it, but I like simple fixes also
 
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Originally Posted by Skippy722
Your downstream power levels are kind of high, ideally you want them at 0 though -10 to +10 is acceptable, while your upstream is kind of low, these should be +40 to +52.

You may have an issue with your drop. I had random reboots and tons of uncorrectable errors, turns out a squirrel or something chewed the coax up at the pole.



The levels are an easy fix just add a 3-way balanced splitter. Any other issues can be anything.
 
Originally Posted by Skippy722
Another thought: sometimes the techs will throw a splitter on to attenuate the downstream signal, which has the side affect of boosting the upstream. If you find a splitter or 2, make sure to double check your power levels, as they may shoot way up.

The signal coming into my house is really hot, like +15. Tech put a splitter with a -7 rating on the line, keeps my power levels between +5 and +9 on average. Probably the "easy" or "lazy" way to do it, but I like simple fixes also



The balance your signal the tech only has the option of adding spilters, attenuator, and or amplifier. Your house has 15DB at demark is high. The tech can not change the tap so resourceful use of spilters has to be done.
 
Originally Posted by dave1251
The levels are an easy fix just add a 3-way balanced splitter. Any other issues can be anything.


Yep, that's exactly what he put in the box.

Originally Posted by dave1251
The balance your signal the tech only has the option of adding spilters, attenuator, and or amplifier. Your house has 15DB at demark is high. The tech can not change the tap so resourceful use of spilters has to be done.


I didn't know that, makes sense though. Thank you for clarifying!
 
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