speters93's profile

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Tue, Oct 27, 2020 6:00 AM

Netgear CM1150v Random Slow Downs

I am on a 600mb plan and own a CM1150v that seems to randomly drop from speeds of ~720mbps to 30-34mbps until I reboot the modem again. The uptime of my full speed is unpredictable and can last anywhere from 10 minutes to 1.5 days.


It looks like the culprit is losing lock on my OFDM downstream channel due to a large amount of uncorrectables. What can I do to remediate this issue?


My modem is connected directly to the coax cable that enters my house.


Signal levels and logs when not working:

Signal Levels - Slow

Event Log - Slow

Signal Levels when working:

Signal Levels - Good





89.1K Messages

1 y ago


And the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) somewhere.


There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.


I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !


Official Employee


6.1K Messages

1 y ago

Hi @speters93

Thanks for using the Forums to share your experience with slow speeds. I'd be happy to take a deeper look into this to find a resolution. To get started, please send me a private message with your full name, as it appears on your billing statement. 
To send a message, click on my name "ComcastChe," then click "send a message." 



3 Messages

2 m ago

Hello. I read this post with interest because I have been having the same problem between a CM1150V and 1GB service for the past year.  Internet stalls happen less often now that the coax between the tap and my home has been replaced.  I am the only person using this tap. Still happens sporadically.

An excellent xfinity tech checked everything to the modem today.  He increased downstream power (and decreased upstream power). He made 2 observations: (1) the 1150V reports the upstream power ranges from 47 dBmV to 49.3 dBmV even though the physical power is 44-45.  (2) His measure of channel 4 shows SNR varying from 25 - 35 dB.  25 is too low.  His bottom line: the modem has a hardware problem.

I'd appreciate knowing if SPeters93 problem has been resolved and the nature of the resolution before calling Netgear.






89.1K Messages


Please create a new topic of your own here on this board detailing your issue (copy your post and paste it there). Thanks. Re-closing this 9 month old dead thread that was improperly re-opened by the new forum software / platform. A known issue that is being worked on.

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