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Internet Issues Netgear CM600-100NAS Cable Modem

MrPMrP Posts: 9
in Connectivity Dec 26, 2018

Just purchased a new Netgear CM600-100NAS Cable Modem to replace my aging Arris sb6120. I was having timeout issues and having to reset it every month. I thought purchasing this new modem would help solve it.


Well ever since upgrading the problem seems to have gotten worse. Internet is constantly slow and times out quite often. I've noticed I've had more delays with both wired and wireless lately.


Main line goes from pole, to inside my house. From there it goes to a 2 way splitter and one output goes to my modem for just the home phone, the other goes to my cable modem. Between that is a wall plate. So from main line to modem I have a 2 way splitter and a barrel connector. 


Had technician come out and said he fixed part of the main line as it looked like it was chewed by squirrels. My levels still weren't that great when he left.


If you need any other information, please ask!!


I'm attaching a screen shot of my cable modem status,  along with the log.


Any help would be appreciated,  thank you.


modem downstream.PNGmodem upstream.PNGnetgear log.PNG


  • reds91185reds91185 Posts: 2,452
    Dec 27, 2018

    If it's at all possible, move the modem as close as you can to the new main line before it splits out to rule out the wiring inside your house as the cause.

  • MrPMrP Posts: 9
    Dec 27, 2018

    I have tried that. Outcome was still the same, horrible connection and super slow.

  • rocketjetzrocketjetz Posts: 130 ✭✭✭✭
    Dec 28, 2018

    Your Power and SNR values look good.  You might want to call Spectrum AGAIN and explain to them that whatever the 1st Tech did or did not do, didn't fix the problem. I would also print out and show the tech what you posted here. I know its a PITA but sometimes you have to call Spectrum multiple times to get the job done. That's the nature of the beast.  The Tech may need to go all the way out to the tap into the ultility pole to ascertain whats happening. I used to get a lot of uncorrected and such although my signals were more or less perfect. They eventually ran a new line from the tap to the house, put it in the ground this time instead of an air-drop, and then had to come back again to find an old filter on the line......it went on and on until it was finally fixed. It Happens. 

  • karlbeckmankarlbeckman Posts: 2,208 ✭✭✭✭
    Dec 28, 2018

    There's no incorrect filter showing up on this one.   But the upstream levels look quite high relative to the downstream after they replaced your squirrel-chewed drop line.   First, a quick internet sdearch says your N600 modem uses the Intel Puma-6 chipset which has bugs that appear when running at speeds above 100 Mbps.  And your modem is only showing corrected and uncorrectable packet error counts on the first 16 channels, not all 24.  It's possible that Spectrum sent your modem the wrong provisioning file.  The file for the new 24 channel Netgear buggy Puma-6 modems is very different from the older 16 channel modem version that worked. 

  • MrPMrP Posts: 9
    Dec 29, 2018

    The CM600 actually uses the Broadcom BCM3384 chipset, where as the SB6190 uses the Intel Puma chipset. That is the reason I purchased the netgear over the Arris as I heard of all the problems people were having with that chipset.


    I'm still on the old TWC legacy plan, the ultimate internet, so 50 down and 5 up. So I don't have any speeds over 100 MBPS yet.


    My levels were always high, pushing the max allowed, which caused lots of drop outs and modem reboots. He then came out and went up the main utility pole in my backyard where all of your taps are and said he replaced a section of coax that was chewed by a squirrel. He was out there quite some time and it was dark out, so how much he really did or didn't do I can't say.


    My line goes from a telephone pole, through the air, then down into my house. It's possible the line could have issues anywhere along it, no idea how old it is either. Probably runs 100' from pole to my house.


  • MrPMrP Posts: 9
    Dec 29, 2018

    See post I just added above, hopefully I added some more information that might help.


    I want to get the 400 down and 20 up, but I think I'll just have even more issues than I'm currently having now.


    I have a ton of uncorrectables, which isn't good. My upload power levels are also high. Might be a line issue?

  • Julia_RJulia_R Posts: 4,207 Lead Mod
    Dec 29, 2018

    I agree, if you are having trouble at the slower speeds you will still have trouble 

    with the faster speeds.


    This needs to be resolved to have a solid connection, raising the speeds would

    more than likely exacerbate the issue. 


    If you would like to schedule or have us help out with direct support, I encourage you

    to contact our Social Media Customer Care team at: 


    Twitter: @Ask_Spectrum

    Facebook: https://www.facebook.com/Spectrum




    Julia R.

    Spectrum-Social Media Customer Care

    Lead Moderator-Community Forums

  • karlbeckmankarlbeckman Posts: 2,208 ✭✭✭✭
    Dec 29, 2018

    Sorry about the model vs chipset confusion.  Note that your Message Subject entry says "Internet Issues Netgear N600 Modem" rather than Linksys CM600.  The N600 does appear on several web lists of "Don't Buy This Modem, It Uses Puma-6," and so does the Arris SB6190.

    As for the idea that a squirrel-chewed drop was causing high receive levels, sorry but NO, it works the other way.  Water getting inside the line reduces the available signal, with more loss at the higher channel frequencies.  The 100 ft drop length is typical for residential service, but the error counts (uncorrectables about same as correcteds) suggest that your home installation still needs to be repaired.

    Your uplink (US) levels should not be that high (above +48) when DS receive is coming in above +7.  Are you sure you don't have an extra splitter in line, or one connected backwards?  The internet  data modem should normally be fed directly, or from the very first splitter from the pole.  Anything else (EMTA telephone modem, DVRs, and TV set-top boxes) splits off AFTER the data modem. 

  • MrPMrP Posts: 9
    Dec 30, 2018

    I apologize for the confusion, I will edit the subject title to clear that up.


    It is a Netgear CM600-100NAS cable modem that I have.


    I am positive that the cable modem is only split once and that the splitter isn't backwards.

    Main line comes into my house and runs to a 2 way splitter. From there one lead runs diretctly to my cable modem to my upstairs closet, about a 20 foot run. It does go to a wall plate, which does add a barrel connector. The other leads goes to another splitter, which then runs to my tv's, cable box's, EMTA modem, etc.


    I have no idea how they have the cable coming off the main pole in my backyard though. I'm assuming directly from the tap, down to my basement?


    I'm not sure what else to try, all I know is this issue isn't getting any better and all my devices struggle to even stream anything anymore. Wifi speeds are horrible, even direct wire connections are struggling to keep up. So their is definitly an issue with the line somewhere.


    I haven't reset any of my devices, as I want to keep track of my levels and Uncorrectables. This is the updated photo as of December 30th @ 12:22pm CST


    new logs cable modem.PNGupstream levels.PNGDownstream levels.PNG

  • MrPMrP Posts: 9
    Dec 30, 2018
    It looks like Channel 8, 14 and 16 are the worst. In the last 4 days:

    Channel 8 Correctables went up 4,100 and Uncorrectables went up 20,000

    Channel 14 hasn't had much change but still high

    Channel 16 Correctables not much change but the Uncorrectables went up almost 4,000

    Their has to be a serious issue. I've never seen them this high before.
  • RAIST5150RAIST5150 Posts: 670 ✭✭✭✭
    Jan 08, 2019
    May be a hairbrained idea... but it is possible there could still be a legacy choke on the line somewhere. Seen it happen before... even caught it at my own house.

    They used to use them to block the tv tuners from picking up the cable channels in the higher frequencies. When in place you will see a dramatic decrease in signal strength/quality around the 500-540mhz end when you look at the range in a spectral analyzer... almost like a hockey stick at 500. Signal is dropping a good bit as you move towards that lower end, and it looks like it has been periodically dropping channels below the 560-ish mark and replacing them with the higher end ones. Those channels are roughly where channels up to around 78 were broadcast back in the day.

    Otherwise, double check the house for wall plates/coax cables that are not attached to anything or don't have termination caps. Open live cables are like micro antennas for LTE ingress from the likes of T-mobile and such that still use frequencies below 700mhz.

    EDIT: Something to keep in mind about that signal page on the Netgears is that the error numbers do not follow the frequencies when it rethunks to bond a clearer channel--they stay bound to the left-most ID number. So if the 10th slot was initially bound to channel 10 at 543mhz, then it dropped it and bound channel 17, it is still keeping the error rate numbers from the previous 543mhz bonding. Can't "resynch" them either... can only reset all counters with a reboot.

    It looks like your issues are initially starting in the first two octaves you are bonding, below 16. You could try telling it to start it's channel searches above that, like channel 17's frequency or 25's to see if it holds up better. It would trigger a sort of soft reboot while it thunks the channel lineup again, but shouldn' t clear the error rate counts... for that you would need a reboot. Not a reset to defaults, just a reboot.

    Keep in mind that this strong arm test would be more a bandaid to mask the issue temporarily if it does show improvement. Those lower channels could still be in play and impact the quality of service. Once you have a tech visit and adjustments are made, you would want to reset to defaults to make sure things improve under the normal operating configuration.
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