CM1000V2 DS light flashing but internet connection is great

[Saint_Dad]

A couple of weeks ago the downstream light on my CM1000v2 started flashing.  I've been using this modem since March of 2020.  The light becomes solid green with a reboot, but it only lasts for 1 to 4 days.  Called the ISP (Xfinity) support and they claimed the line was fine up to the modem and therefore my modem was the likely problem.  I purchased another CM1000v2 and it displays the same issue after 2 days.  Connection shows 32 downstream bonded channels locked with correctable codewords = 0, and Uncorrectable = 0.  Downstream OFDM Channels has 1 locked with correctable codewords = 1558088684, and Uncorrectable = 3.  I have speed tested and am getting and average download speed of 940 Mbps and no connection issues.  I'm curious if the blinking DS light is a result of the 10.01.07 FW update, and simply a firmware bug with no effect on performance.  My wife relies on our network for work, so I'm trying to get ahead of any possible problems.  

[Saint_Dad · Accepted solution]

Problem solved.  Replace the section of coax in the attic.  The connectors were installed poorly. Used a quality quad shied rg6 and compression connectors.

[olympos1625]

Hi @Saint_Dad,

Good day!

Thank you for reaching out. The blinking light behavior on the downstream LED indicates that the modem is scanning for a downstream channel same goes for the upstream LED if it will have the same behavior. You may check this information from the link below page 6:

https://www.downloads.netgear.com/files/GDC/CM1000/CM1000_UM_EN.pdf

Please do not hesitate to let me know if you need further assistance. 

Regards,

Oliver

Community Team

[Kitsap]

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@Saint_Dad wrote:

A couple of weeks ago the downstream light on my CM1000v2 started flashing.  I've been using this modem since March of 2020.  The light becomes solid green with a reboot, but it only lasts for 1 to 4 days.  Called the ISP (Xfinity) support and they claimed the line was fine up to the modem and therefore my modem was the likely problem.  I purchased another CM1000v2 and it displays the same issue after 2 days.  Connection shows 32 downstream bonded channels locked with correctable codewords = 0, and Uncorrectable = 0.  Downstream OFDM Channels has 1 locked with correctable codewords = 1558088684, and Uncorrectable = 3.  I have speed tested and am getting and average download speed of 940 Mbps and no connection issues.  I'm curious if the blinking DS light is a result of the 10.01.07 FW update, and simply a firmware bug with no effect on performance.  My wife relies on our network for work, so I'm trying to get ahead of any possible problems.  

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I always considered such comments from Xfinity to be a dig or a slap because I own my own modem and no longer contribute to their monthly device rental revenue stream!

Since you own your own modem, there are limits as to how much information support personnel can see from their end.  I think it varies from modem model to model.

A gradually degrading condition normally indicates buildup of a capacitive charge on the line.  The usual culprits are loose, corroded, or poorly installed coax connectors anywhere between the modem and the drop connection in the street.  Another contributor can be loose or corroded ground conductors at the service box entrance on the side of your house.

It would not hurt to do a copy and paste of your cable connection channel details into a word processing document and attach to your reply.  Sample attached to this message.

[Saint_Dad]

Thank you for the suggestions. I’ll check the connection at the outside box. I’ve also looked at the line between the outside box and the wall socket for my modem. There a section that was added to extend the cable from the family to living room. It has been working fine for 20 years, but I plan on replacing it. After all the work on my end is completed, I’ll push more on Comcast.

[Kitsap]

!

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@Saint_Dad wrote:
Thank you for the suggestions. I’ll check the connection at the outside box. I’ve also looked at the line between the outside box and the wall socket for my modem. There a section that was added to extend the cable from the family to living room. It has been working fine for 20 years, but I plan on replacing it. After all the work on my end is completed, I’ll push more on Comcast.

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All the more reason to check it carefully and/or have it replaced!

[Saint_Dad · Accepted solution]

Problem solved.  Replace the section of coax in the attic.  The connectors were installed poorly. Used a quality quad shied rg6 and compression connectors.

[Kitsap]

Glad you have it taken care of.  Please mark this issue as resolved so others can benefit from the discussion.