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ODFM Errors in Modem?

MachineXMachineX Posts: 3 Spectator
in Connectivity Aug 05, 2022

I recently upgraded from the Ultra to Gig internet service. In the process I decided to get a personal modem, with known better performance (Motorola MB8611). It is also on the preferred list for Spectrum service.

For the most part things seem to be OK, however I notice what I believe to be a large/unacceptable number of errors on one of my modem channels. In this case is is channel #25, and is the only one that looks different being "OFDM PLC" where all others are "QAM256".

Is this normal, or something I should be forcing Spectrum to look into? They have been out a couple of time over the last week to troubleshoot issues with my Tuning Adapter/Tivo integration, which is now resolved, and I have brought it up to all the techs that have visited., but none have suggested there is any issue.

Thoughts? Appreciate any insights, suggestions, etc.




  • William_MWilliam_M Posts: 349 Moderator
    Aug 05, 2022

    Hi @MachineX, welcome to our community!

    Are you having any actual problems with the internet service, or are you just concerned by the errors shown in the log?

  • MachineXMachineX Posts: 3 Spectator
    Aug 05, 2022

    A little of both. Obviously the number of errors is disconcerting. Additionally from time to time, my upload speeds fluctuate quite a bit. Some really strange numbers from time to time. These are speed tests performed directly from my router.

    As I understand it, I should have 1Gbps down, and 40 Mbps up. I realize you never get that in real life, but some of these seem rather off, especially figuring the times (non high utilization hours).

  • Paul_BPaul_B Posts: 505 Moderator
    Aug 05, 2022

    Thank you for the speed test results. We were able to locate your account information using your forum registration information. I took a look at the modem and I am not seeing anything out of the ordinary. It is difficult to tell from your screenshot. Are the errors that you're seeing showing up in the corrected column? In my research, these can usually be ignored as corrected errors are normal.

    Please let us know if you have any additional questions, and we can continue to take a look for you.


  • MachineXMachineX Posts: 3 Spectator
    Aug 06, 2022

    So, in general recently I generally do not get more than 3/4 of my upload speed (around 30Mbps) instead of the 40Mbps expected, except for rare occasions.

    In regards to the ODFM I rebooted my router 7 hours and 24 min ago. Since then the channel 26 (OFDM PLC) has had 1,798,107,181 corrected and 5406 uncorrected.

    It is hard for me to imagine that 1.7 billion corrected is considered normal, when no other channel shows anything near that.

    The only complaint I have is that I am not typically getting my advertised upload speeds.

    And of course the numbers I am seeing on the ODFM channel are very confusing, I never saw anything like this on the old Ultra service/modem. Can you please explain why this is such a high number?

  • William_MWilliam_M Posts: 349 Moderator
    edited August 6 Aug 06, 2022

    The upload speed provided with Spectrum Gig is only up to 35 Mb/s upload, not 40 Mb/s. While the number is unusually high, correctable errors are generally not considered a problem especially without a corresponding service issue.

    I recommend making sure the coaxial cable is firmly connected on both ends and that it is not kinked or pinched anywhere. If possible please run any speed tests using a device connected with an ethernet cable directly to the modem, bypassing your router, to see if you can get closer to the 35 Mb/s upload instead of 30. Other connected devices may be using a small amount of upload in the background which can affect your test results.

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