NETGEAR is aware of a growing number of phone and online scams. To learn how to stay safe click here.
Forum Discussion
CM2050V - Latest Firmware Preventing 2.5 Gbps Passthrough on Ethernet Port
Hello all, and specifically to the moderator,
I'm reporting a potential firmware or hardware version defect where the native Ethernet port fails to pass through 2.5 Gbps speeds to the LAN, with firmware v10.01.03 (around February 2025).
Modem details:
Hardware Version: 1.01
Cable Firmware Version: V10.01.03
Note that this is one of the first series of the modem purchased back in March of 2021. It has been in service as a reliable work horse since then (with the exception of the botched FW v9 update). The unit is out of warranty, but still performs reliability (except for this latest defect).
The defect:
This issue surfaced after Comcast auto-upgraded my plan from 1.2 Gbps to 2.1 Gbps plan; a routine speed tests showed no improvement, maxing out at ~986 Mbps instead of the expected 1800-1900 Mbps (accounting for overhead).
Key evidence:
1. Via SSH to my router, the WAN port negotiates at 2500 Mbps full duplex:
eth0 (Int switch port: 3) (Logical Port: 3) (phyId: 1e) Link Up at 2500 mbps full duplex
2. A direct connection tests to the modem's Ethernet port:
Using my Fluke Networks CableIQ tester: Max output ~986 Mbps.
3. Xfinity onsite tech visit: Confirmed excellent coaxial signal levels from street to modem (provisioned for 2.1 Gbps). Their better and more sophisticated Ethernet tester replicated my results at ~987 Mbps directly on the modem eth port. Additionally their tester showed the ISP service side of the modem and he ran diagnostics and reviewed the modems frequently, power and SNR levels and all appear as expected (normal).
Conclusion:
ISP (Xfinity) confirms upstream provisioning and signals are optimal; the bottleneck is within the modem.
This appears to be a firmware or perhaps a hardware version limitation preventing full 2.5 Gbps Ethernet passthrough. Since firmware updates are ISP-controlled, Netgear must coordinate a fix release.
ISP Details:
Xfinity, plan 2.1 Gbps Down / 300 mbps UP Internet
Moderator: Could you please confirm and respond on:
A. If engineering is aware and working on a fix for imminent rollout?
B. If this is new, will you escalate for investigation and potential correction?
C. Is this a possible Hardware v1.0 issue, and if so, what version is the newer CM2050V's HW Version and do they suffer the same problem?
Thanks for your attention – eager for a resolution.
10 Replies
Theres only one HW version of the CM modems.
What is the brand and model# of the host router connected to the CM modem?
What speed test app or site are you using to check speeds?
It would appear that the Fluke CableIQ tester is rated for gigabit Ethernet. Might lead to a conclusion that it is not capable of measuring higher speeds.
Does this router include a Speed Test that can be run on the router itself?
Would be really helpful to have a computer with a 2.5GB Ethernet adapter that could be connected directly to the modem to run a speed test.
It is not obvious (to me) how a customer would open a support ticket on a product purchased in 2021 (four years ago).
CrimpOn,
Thanks for the reply.
I miss identified the Fluke tester in the OP, it was the LinkIQ which is capable of 10 Gbps (borrowed from work). However note, that the Xfinity tech's ethernet tester was also rated at 10Gbps, and it also showed 987 mbps consistently, so the two test equipment were consistent.
As far as the router question, Yes, it has the build in speed test and along with other devices on the network was used to first identify the anomaly.
The router has a 2.5 Gbps WAN port and as stated in the OP, negotiates at 2500 mbps Full Duplex. Prior to the v10.01.03 updates (and still on the 1 Gbps plan), I was able to consistently achieve 820's to 1012 mbps using the built in speed test. The speed test numbers have not changed ( I still get those speeds), on the new 2.1 Gbps plan), but I'm not getting the 1800-1900 mbps that the new Xfinity plan provides, and caps out at the 900 mbps range.
The cable connection at the modem is 2300 mbps, but once passing through the modem and out the ethernet port of the modem, it drops to 987 mbps (tester directly connected to the modem).
This would in theory indicate some kind of internal issue of the modem (I was at first thinking hardware version, but FURRYe38, indicated that all the models of CM2050V have the same HW version), so HW version was ruled out at this point, unless there is a way to internally check the ethernet PHY for compliance, and it passing all consumer and ISP operator diagnostic, it is not apparent that the PHY is the problem.
Regarding the support ticket, I agree! Although these modems are ment to have at least a 7-10 year life span (or until DOSIS 4 arrives), it should be support for "firmware/internal", and the consumer should have a simple way to open a ticket for FW/HW level issues.
All of the consumer and ISP Operator level troubleshooting has been exhausted at this point, so I am not looking for things to try outside of the modem, as all of the standard and professional tracing/troubleshooting back to the modem for a problem has been done. All logs and connections status have been verified by Xfinity as good.
You'll need to make contact with NG support then.
Thanks for the reply, and for confirming the HW version for all models is V1.0
As mentioned in the original post, the router is not part of the equation and has been completely removed from all testing (except for the initial speed test that identified the issue).
Both a Fluke LinkIQ (I mistakenly called it CableIQ in the OP) and the Xfinity tech's more sophisticated cable and ethernet testers, both connected directly to the modem with a short certified patch cable specifically designed for these types of testers, produced identical results (within a slight 1k variance, as noted in the OP).
Xfinity confirmed that upstream provisioning is normal, and this would indicate the bottleneck is within the modem. Since HW version doesn't appear to be a factor, firmware would be the next logical item to pursue. Unless the modem's 2.5 Gbps port capability, as stated in Netgear's marketing materials, isn't fully achievable in practice (which I doubt since prior to FW v10.01.03, I was able to get 1022 +-100 mbps using speedtest.net and nperf.com (and yes, this is a highly optimized network).
Regarding support: The modem is out of warranty based on purchase date, so standard support requires a paid plan. Is there a way to open a ticket specifically for firmware related issues, as this might be covered without cost to the consumer? I am unaware or able to open a firmware ticket, do you have a link or contact within Netgear where I can do this?
From all indications, the modem seems to be functioning as intended. The Xfinity onsite tech's diagnostics passed on their devices (including the Ethernet tester mentioned and a cable tester from the ISP side). It's unlikely the Ethernet port is faulty, as it negotiates at 2500 Mbps full duplex.
My aim is to highlight this publicly in hopes Netgear can investigate the cause and provide a workaround or solution to fixing their ethernet port on this modem. All of the consumer and ISP Operator level troubleshooting has been exhausted at this point. I'd appreciate any input from DarrenM on my three original questions.
Please post a copy and paste of the modems connection status and event log page.
https://kb.netgear.com/30007/How-do-I-obtain-the-cable-connection-information-from-a-NETGEAR-cable-modem-modem-routerhttps://www.netgear.com/support/contact/
FURRYe38,
Sorry, I can't publicly publish any logs or status of the modem (or any connected system) due to security and privacy of this network, I appricate your help and understanding on this matter.
Regarding Frequency, Power, and SNR they are all were in spec, and the required number of bonded (Downstream Bonded Channels, Upstream Bonded Channels, Downstream OFDM Channels, and Upstream OFDMA Channels were correctly working for the 2.1 Gbps Service. There were no discernible errors in the log that would indicate anything other than optional operation.
So until we hear from DarrenM and feedback from Netgear (hopefully he can get this pushed through), there are no consumer side settings in the modem that can be looked at or changed. I'm satisfied with Xfinity through review of not only the network connections and method of testing, but also that the modem is operating as expected, apart from not passing through 2 Gbps to the ethernet port.
One other consideration.....
Is the issue that all CM2050V modems top out at 1GB, or only this CM2050V modem?
- Netgear's Product Data Sheet is explicit in claiming speeds to 2.5GB
https://www.netgear.com/images/datasheet/networking/cablemodems/cm2050v.pdf - Comcast (Xfinity) lists the CM2050V as supporting download speeds to 2.32GB and upload to 485MB
https://www.xfinity.com/support/internet/customerowned - If all CM2050V modems cannot exceed 1GB download speed, one would think there would be serious conversations going on.
- If only this one, four year old CM2050V is faulty, then the solution would be to replace it with a modem that works correctly.
Do the techs carry spare cable modems on the truck?
Amazon has a pretty liberal return policy. What about buying a "refreshed" CM2050V for $149. If it fails, return it. Reason: it doesn't work correctly. If it does work, then that adds to the possibility that the original CM2050V has bit the dust.
- Netgear's Product Data Sheet is explicit in claiming speeds to 2.5GB
another crazy consideration. Xfinity claims that the account has been configured for 2GB download and the tech claims that the Netgear CM2050V modem is at fault.
Great. Let the tech install a modem from the truck and demonstrate that HIS MODEM provides 2GB download speed. If his works, dump the CM2050V and buy a new modem.
(Digression: Last year, I had a problem with the Tuning Adapter Spectrum supplied to enable my Tivo to function [required by the FCC]. A technician spent 8 hours [his entire shift] working on the problem. Installed 4 different Tuning Adapters. Replaced cables and connectors. 8 hours! After he said, "sorry. Can't fix this" and left, I called Spectrum one more time. A nice woman said, "hmmm. your account is not coded correctly. Can you try the Tuning Adapter again?" We spent a full day trying to solve a problem that wasn't there in the first place.
It would be crazy to find that Xfinity told you that the account had been changed to support 2GB download, but that it was not actually set up to do that.)
