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Re: CM2050V goes offline every few weeks - how to troubleshoot

SethSea
Aspirant

CM2050V goes offline every few weeks - how to troubleshoot

My Netgear Nighthawk CM2050V cable modem, purchased earlier this year, linked to Comcast service has been going offline every few weeks for the past two months.  Comcast cannot find an issue. Powering the modem off/on fixes the issue. How do I troubleshoot the cause of this issue to identify the cause: Comcast, hardware, software, other?

Hardware Version: 1.01

Firmware version: V9.01.01

 

Thank you in advance for any help you can provide.

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FURRYe38
Guru

Re: CM2050V goes offline every few weeks - how to troubleshoot

Message 10 of 10

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FURRYe38
Guru

Re: CM2050V goes offline every few weeks - how to troubleshoot

Message 2 of 10
SethSea
Aspirant

Re: CM2050V goes offline every few weeks - how to troubleshoot

Thank you for responding. Per your request, I am providing cable connection status and event log. Also, I am providing event log export, with "gif" extension to allow upload.

 

Due to the one file attachment limitation I will upload each separately. 

 

The connection status is attached to this post.

Message 3 of 10
SethSea
Aspirant

Re: CM2050V goes offline every few weeks - how to troubleshoot

Attached is event log.

Message 4 of 10
SethSea
Aspirant

Re: CM2050V goes offline every few weeks - how to troubleshoot

Attached of event log export in binary format with "gif" extension failed on Post.

 

Please let me know if you need any additional information.

 

I appreciated the links to "how to" articles.

 

Thank you 

Message 5 of 10
FURRYe38
Guru

Re: CM2050V goes offline every few weeks - how to troubleshoot

So power levels are good along with Correctables and Un-Correctable values. 

 

Any Criticals, Errors or Warnings seen in the event logs needs to be reviewed and resolved by the ISP. Indicates a signal issue on the ISP line up to the modem.


Be sure your using a good quality LAN cable between the modem and router. CAT6A STP is recommended. 
What is the brand and model of the host wifi router connected to the modem?

 

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
https://highspeed.tips/docsis-events/

Message 6 of 10
SethSea
Aspirant

Re: CM2050V goes offline every few weeks - how to troubleshoot

Thank you for taking the time to provide a detailed response. The Duckware link was particularly helpful.

 

I would appreciate your opinion on where the problem lies - hardware, ISP, software, other? I do not want to buy a new cable modem to find out it does not solve the problem

 

Before posting to this site, I contacted Comcast. They performed tests from the host side and said the connection looked good. A serviceman came out and said the connection looked good at the modem and suggested replacing the CM2050V with another one. I have looked through the modem logs and see a couple of critical errors that happen every now but they do not seem to be interfering with the modem - despite the errors I have not experienced any problem and the modem has stayed online.

 

I have attached a "Cable Info" report from this morning. Do you see issues that I should contact Comcast about? As far as I can tell, other than the critical errors (maybe benign), everything looks great (following the troubleshooting in the Duckware article).

 

As I purchased this modem earlier this year, I cannot get Netgear support without buying a contract.

 

Again, thank you for your advice.

 

 

Message 7 of 10
FURRYe38
Guru

Re: CM2050V goes offline every few weeks - how to troubleshoot

Still seeing some Warnings in the logs. Something the ISP should look into. Otherwise, looks ok.

What FW is on the modem.

 

Just FYI on what some others are seeing:

https://community.netgear.com/t5/Cable-Modems-Gateways/CM2050V-unstable-after-Comcast-updated-firmwa...

https://community.netgear.com/t5/Cable-Modems-Gateways/CM2050V-unstable-after-Comcast-updated-firmwa...

 

 

Might ask about this from your ISP. 

Message 8 of 10
SethSea
Aspirant

Re: CM2050V goes offline every few weeks - how to troubleshoot

Hello FURRYe38,

Again, thank you for your helpful comments. Your help and patience has paid off as there appears to be a resolution in sight based on an email from Comcast I received today (see below). You asked for the firmware version on my modem. It is V2.01.03.

 

A minor question. Previously I was able to generate a "Cable Information" report from the web interface. Now I cannot find the link to do that. Do you know where it is? The report (see attachment to post in this thread on Nov. 26, 2023 at 16:31) is a great comprehensive dump of diagnostic information.

 

What I heard from Comcast today follow. In summary: Netgear software issue.

 

We've noticed intermittent connectivity issues with your internet service and have identified the cause to be a defect with your NETGEAR CM2050V internet modem. NETGEAR is working on a software update that should fix the problem. Because the update may not be available for several months, we have taken steps in the interim to stabilize your connection and provide you with the best possible experience. These proactive measures should resolve your intermittent connectivity issues and provide you with fast speeds, but your modem may not achieve the full upstream speeds included in your Xfinity Internet package until the NETGEAR CM2050V software update is deployed.

 

I assume there are a number of Comcast/Xfinity customers who are having a similar issue. Hopefully, they will find this resolution before going out and purchasing a new modem as I was advised by Comcast technician. Fortunately, your advice saved me from making that expensive mistake.

 

Best wishes

Message 9 of 10
FURRYe38
Guru

Re: CM2050V goes offline every few weeks - how to troubleshoot

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