1113361's profile



28 Messages

Sat, Dec 26, 2020 7:00 PM

Connectivity Issues with 3rd party modem (Netgear CM1150V) - Comcast Tech Request Please


History of my issue

CM1150V on Xfinity 600Mbps plan

Worked perfectly for almost a year - consistent full spec speeds 

Around mid Nov, began to have frequent drop-outs and occasionally throughout day but EVERY morning would have to power cycle modem to re-establish connection 

After dealing with that EVERY DAY for about 2 weeks, called out Xfinity. 

Xfinity Tech checked lines all way to street interface - no issues, installed Xfinity XB7 and all was perfect (immediate and consistent thereafter); 

Felt confident this was a hardware issue as it appeared the XB7 resolved the issue i.e. it worked consistently, the CM1150V did not. 


Received replacement CM1150V 12 days ago and re-commissioned with Xfinity

Initially worked perfectly and consistently for 10 days then suddenly 2 days ago began having identical issues to first one 

(this makes me wonder if in both instances a firmware 'upgrade' was pushed by Xfinity?) 

(have since learned this is the std firmware at this time, so I don't believe that to be the case- I can also see that my signal levels are now higher than they were a couple of weeks ago) 


Here is log from the last 12 hrs or so - note that this was while the Modem was essentially unused during the night! 

Came down this morning to find no internet connection and attached is the Event log showing the period of preceding 12 hrs or so 

6:44am is when I power cycled the Modem, so those errors pertain to that. 

(after power cycling the modem it came back on line at full download and upload spec speeds - this behaviour is consistent with that of the initial modem after a power cycle) 


I have included images of the Event Error Log, the Baseline Modem Status when it was working perfectly when installed on 12-15 and the Modem Status yesterday (when there was no Internet Connection) 




Only differences I see in the Modem Status are: 

The Download Frequencies are much higher generally in the baseline 

There is a high incidence of 'correctables' in the problem status of yesterday 


Other interesting notables

When a Download has been established and continuous (e.g. such as streaming a movie or live sports through my subscriptions) it tends to remain consistent until there is a break in download traffic (once it has been idle, it will not re-establish a connection) 

Another way to recover the connection besides the Power Cycle of the modem is just to keep requesting a Speed Test (I use the Ookla App downloaded on my devices)  - this one is curious - I can request multiple times and it fails, then finally it will connect with very slow download speed (only a few Mbps) initially and then the upload part of the test is at full spec (18Mbps); the very next speed test (run immediately after) will deliver full speed down and up. 

A modem power cycle will immediately re-establish full spec speed once reboot completes. 

The behaviour is now identical on second modem as was the original 

Both Modems were performing perfectly & consistently before suddenly becoming consistently problematic (again this makes me suspect a firmware upgrade?) 

But almost certainly rules out Hardware 

The XB7 had zero issues during its 3 weeks installation (and problem was consistent with initial CM1150V prior to the XB7 install which instantly resolved it)  


What does the log indicate was going on during that night time (supposedly idle) period? 


- can you take a look at this?  





Official Employee


276 Messages

6 m ago

Hi there! I'd be glad to ensure that this gets looked into further. Please click on my handle (ComcastRob) and send a private message with your name, the complete service address (including city, state, ZIP, suite number, etc), and the phone or account number, and any pertinent details-- like the ticket number(s)-- so we can help. 


Official Employee


276 Messages

5 m ago

Hello @1113361, I wanted to follow up with you to see how your service is running since our last communication. I did see that you mentioned your service came back on, but I wanted to see if you ran into any further issues? Also, you had mentioned that your were looking to repackage your service, as you did not use your Xfinity voice service very much. Would I be able to help you with this. Please click on my handle (ComcastRob) and send a private message, if you need further assistance.

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