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Netgear CM3000 – Firmware v6.01.03 Causing Constant Disconnects
Hi all,
I’m on Spectrum’s 1 Gbps plan and use my own Netgear CM3000 modem. It recently updated to firmware v6.01.03, and ever since then it drops connection every few minutes. On the previous firmware (v5.01.02) it was completely stable.
Symptoms and errors:
- Frequent disconnects with T3/T4 timeouts.
- Errors showing in the modem event log include:
- SYNC Timing Synchronization failure
- No Ranging Response (T3 timeout)
- Missing BP Configuration Settings
- TFTP Request Retries exhausted
- SW Download INIT via NMS / TFTP Request not acknowledged
- REG-RSP Mismatch Between Calculated Value for Fh
Troubleshooting already done:
- Signal levels confirmed to be within spec (SNR, downstream power, upstream power).
- Direct coax run (no splitters).
- Tried bypassing my router — still disconnects.
- Factory reset the modem.
- A Spectrum technician came out and confirmed the line is healthy. With a Spectrum-provided modem, the connection is solid.
This makes it clear that the issue is firmware-specific to v6.01.03 on the CM3000.
Request:
Is Spectrum aware of this issue? Can this firmware be rolled back to a stable version, or is there a timeline for an updated release? Right now I’m stuck using Spectrum’s modem just to keep a stable connection, but I’d prefer to use my own equipment as before.
Thanks for any guidance here!
Comments
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Hello @ConnK;
Welcome to the Community Forums. Our engineers review the firmware for any issues and apply it automatically. At this time there is no way for us to push a different firmware to the modem. I see the modem was switched out and because of that I am not able to see the historical data of the cable signals. Currently the modem is online with good signals. It also has not registered T3 timeouts today. I would recommend you give the new modem some time to see if it resolved the issue. If you continue to see problems with the connection then reach back out to us and we can review the historical data of the modem to see if there is any issues that need to be addressed.
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Thanks for the reply. I understand Spectrum controls firmware distribution and that rollbacks aren’t normally possible. The issue I’m raising isn’t about my individual signal, but about the fact that firmware v6.01.03 on the Netgear CM3000 is introducing repeatable failures:
- Frequent drops every few minutes.
- T3/T4 timeouts, ranging failures, and TFTP retries in the logs.
- Stable on v5.01.02, but immediately unstable on v6.01.03.
I swapped to a Spectrum-provided modem for stability, but this effectively forces customers away from using their own approved equipment. Could you please escalate this to engineering so it’s at least logged as a potential firmware regression? If others on CM3000 hardware hit the same issue, they’ll run into the same wall unless it’s tracked.
I don’t need immediate rollback, but I’d like confirmation that engineering is aware of the issue with v6.01.03 and that a fix or replacement firmware is being investigated.
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I have the same modem with the same firmware. Having a similar problem with constant disconnects. It boots, gets internet, and then reboots after it completes a download. The below line shows in logs:
SW Download INIT - Via NMS
Then the success…and then the modem reboots itself. Process repeats. Picture of the events for reference. Immediately after the download success - the device reboots and the process repeats.1 -
Side-effects notwithstanding, you all might as well try to read between the lines until the OEM itself has anything to say or publish about any firmware update being so widely and rapidly deployed.
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Hi @jcmars, welcome to our community. Sorry to see you're having this issue as well. Just to let you know, I've removed your duplicate post about this so please look for responses here.
@HT_Greenfield good catch! I also saw something similar on reddit. It appears to be impacting multiple (all?) providers, the common factor is the CM3000 modem with v6.01.03 firmware.
I am working on escalating this to our engineers to see what options are available such as a rollback. My recommendation is to use a Spectrum modem, they are free and more importantly will still work once network evolution/high split is completed in your area.2 -
having the same issue with my cm3000 as well. Boots up for about 3 minutes, turns off, and it repeats the cycle. Everything points to the new firmware pushed out from v5 to v6. Contacted support, they stated they do not have any signal on their end going to my modem. Firmware basically bricked our device. Do not know if spectrum will revert the firmware at all. To avoid any further issues in the future, just going to swap it out for a s33 or 34.
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@William_M Opened a support ticket with them to see what can be done - appreciate the info!
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Thanks for the follow-up, @William_M. I’m a bit concerned, because I’ve now spoken to both Netgear and Spectrum support, and I’m getting conflicting information:
- Netgear explicitly told me Spectrum controls and deploys firmware updates for the CM3000.
- Spectrum is now saying you haven’t deployed any firmware updates and to contact Netgear.
My understanding has always been that Netgear develops the firmware, provides it to Spectrum, Spectrum reviews/approves it, and then Spectrum distributes it to customer modems. If that process is correct, then it seems like there’s a breakdown in communication between Spectrum and Netgear about what has been deployed.
The problem is that users (myself and others in this thread) all started experiencing the same disconnects immediately after the CM3000 was updated to v6.01.03. Another Spectrum-provided modem on the exact same line is stable, so this points directly to firmware on the CM3000.
I understand individual troubleshooting isn’t possible without the old modem connected, but this issue goes beyond a single customer. It would really help if engineering could clarify:
- Who exactly controls CM3000 firmware distribution (Spectrum or Netgear)?
- If Spectrum does deploy firmware, can engineering confirm when v6.01.03 was rolled out?
- If Netgear does control it, can Spectrum escalate with Netgear so customers aren’t stuck in the middle?
Right now, customers are getting caught in a loop where Netgear blames Spectrum and Spectrum blames Netgear. Meanwhile, CM3000 users are left with broken service.
Please escalate this so we can at least get clarity and accountability.
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thanks for the reply. issues came about after firmware. To avoid going in circles, I switched over to an Arris cable modem. Reviews and overall performance is a good alternative. Not worth the headache of going back and forth with support.
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- ISP's have network stability and security to worry about
- If that means collaborating with manufacturers, so be it
- Enter Manufacturer Control Scheme as needs be
- Patience is a virtue until the manufacturer has anything to say or publish about it
🔗 https://www.cablelabs.com/specifications/CM-SP-CM-OSSIv3.1?v=I27 ↳ 🔗 Download Doc (4.06mb) = CM-SP-CM-OSSIv3.1-I27-250219.pdf : 8.2.3 Secure Software Download ↳ … manufacturer control scheme … ↳ Figure 6 - Manufacturer Control Scheme
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I’d like to post on this as well. Florida just had a major storm on Monday leaving me without service for 8+ hours. Tuesday service was spotty with several disconnections. Wednesday I was in the dark. Fearing that I had a bricked modem, I swapped to an older model that worked fine. So fancy me, went out and bought a newer version of the same CM3000 ( limited choices in my general area). Installed, and BOOM, same issues as the other model. While you say you haven’t deployed v6, I just looked and both units are on firmware v6. What is our recourse at this point, if we can’t change it, your saying that it hasn’t been deployed, yet our devices show it.
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Just had the same issue. We are 2 engineers working from home and lost 2 days worth of work because of this. Unacceptable.
Spectrum tech suggested it was a floating neutral. Electric company and electrician confirmed electricity to house was working well.
Spectrum approved and pushed a bad firmware update effectively breaking the first modem. Second (same brand and model) modem worked Monday and Tuesday before ALSO receiving the bad firmware version from Spectrum and exhibiting same behavior. Third modem is a different brand with a working firmware and no problems.
There were never any electrical problem that was a red herring from the Spectrum tech…
Now I’m left with a 7 month old $300 modem that is basically paperweight. Argh.0 -
Exact same thing here. My modem reboots, lots of "no ranging response", then a "SW download init", then a reboot. Rinse and repeat forever. So I take it Spectrum has bricked my $300 modem so I can get their 15 year old Arris with terrible ping?
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Wonder if they are having trouble latching upstream.
Have seen this happen with older 3.0 modems after we lost some upstream frequencies in preparation for the 3.1/high split channel changes. We used to have 4x 3.0 upstream channels, but they took the first two away.
The modems would step through power levels on different frequencies until they hit the power limits 51+) and reboot/rethunk until they hit a working frequency. Could take an hour or more to get a lock. Heaven forbid there was bad noise on a line or other conditions that could trigger it to start seeking again... could make for a bad night indeed.
Might help the engineers if some signal status pages were shared. Can usually override Netgear's error message and continue to the status page once primary downstream latches and it is still trying to negotiate upstream and see the frequency, power level, and such it is trying to latch.
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grrr… site is not cooperating with the Samsung browser tonight. Gave me an error message and caused me to double post.
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This is not about frequencies or noise. The modem does a SW Download INIT - Via NMS the moment it gets a connection. It then reboots and the process repeats. You can actually get it online if you keep pulling the power momentarily as soon as it gains a connection. After doing that a bunch of times, you'll eventually see in the log "SW upgrade Failed before download-TFTP Max Retry Exceeded". It will then stay online but I only get a fraction of my normal gig down x 35 up speeds. I get about 95 down and 7.5 up. So it is potentially not provisioned correctly for gig although I see all the same channels as I did yesterday before this problem started.
Diagnostics attached0 -
Hmm... perhaps an issue at TFTP/SNMP. Like the DB has bad nformation on a specific revision or something. Netgear has made a lot of little changes over time on some models.
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Even if Netgear and/or Spectrum provide a fix now, how will the fix be applied to my bricked modem?
Furthermore, this issue could theoretically happen again with any modem/model regardless of the brand (unless it's a Spectrum provided modem). How will this issue be prevented in the future?
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Who do we need to speak to for a real solution here?
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With the "bad" call for FW update shown in MikeyFL's log a couple posts back, hopefully it is just a matter of updating config files/DB entries to get things back in synch again. Sounds like it eventually does "function" once it exhausts retry limits but is grossly misconfigured.
But waiting for validation and such could take a while.
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We have reached out to our network engineers and given them details of the issues reported in this thread. We are awaiting a response and will provide an update here.
Thanks for your patience.
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I'm immediately looking at xfinity coverage in my area
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Same problem here. New firmware appeared and constant reboots. Works for a minute, signals levels all near perfect, speed fantastic, then a couple of minutes later it reboots. Rinse and repeat.
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same problem here. A couple days ago Cmd 3000 started to reboot constantly. Spectrum suggested to contact Netgear. Netgear send me a new Cmd 3000. Contact Spectrum to set up the modem, same problem Cmd3000 started rebooting every 4 minutes. Now I’m having to use spectrum modem in order to have internet. If it’s a firmware issue, then spectrum should do something about it.
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