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Really odd modem problem that happens at a random (but mostly constrained) time of day.

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Frequent Visitor

Really odd modem problem that happens at a random (but mostly constrained) time of day.

Hello Community!

I'm hoping you might be able to help advise me on a puzzling situation with my Technicolor CGM4140COM modem. I've had Xfinity out a number of times to fix but they can't identify the issue without a repro.

Any devices connected to LAN and Wifi will lose network connectivity - as if the modem is suddenly rebooting. It shows no physical signs of rebooting that I can see.

- Both LAN port lights slowly flash at the same time

- XFi app from phone (accessed via cell network)  says it can't connect to the modem

- Local network comes back first

- Internet comes back a few minutes later

- Once the connection comes back I'll resume whatever I was doing (eg. streaming video) and often the connection will drop again in the same manner and take a few minutes to come back.

 

- This happens almost every day but days can go by without it happening.
- This happens mostly between ~10:30am and ~2:00pm. Very rarely earlier or later than that.
- The modem logs don't show any evidence of issues - the uptime/LAN/Wifi uptimes are all as expected (eg. 10 hrs uptime when this problem happened 20 minutes ago).

Other context:

- This didn't suddenly start happening during covid homeschooling, it's been happening for at least 2 years now.

- I do go over the 1.2Tb cap each month.

- The modem is in a workroom and connected directly to the cable socket.

- The big Xfinity adapter thing with the green light is down by the TV connected to a splitter.

- Up/Down Power and SNR seem to be within tolerances.

 

Some random events that (by coincidence? happened at the same as the connection dropping:

- Door slamming.

- Doorbell ringing.

- Electric kettle boiling.

- Load aircraft overhead.

 

Any thoughts really would be greatly appreciated, especially as this is now impacting my kids ability to engage in online classes effectively.

 

Thanks!
SeattleCableDude

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Frequent Visitor

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Forgot to say:
- the modem has been replaced at least twice.

- Multiple engineers have found nothing wrong with wiring/hardware/etc

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Frequent Visitor

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

More data, since this just happened again.

 

- Local network is accessible the entire time, it's just the internet connection that stops working. For example, I can still connect to the Modem on 10.0.0.1.

 

- This is what I observed from the Modem when the connection first went down:
(Multiple Bonded channels)

seattlecable1_1-1603912843838.png

 

Then, a few moments later, I refreshed the page and saw this:

(2 bonded channels)

seattlecable1_0-1603912767281.png

Before it returned to this again:

seattlecable1_2-1603912911240.png

 

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Expert

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Can't see your pics. Since you are a new poster, they need to be approved by a Forum Admin. That could take some time. In the interim, you could try hosting them at one of those free third-party pic hosting sites like Imgur or Photobucket and post the link to them here.

Or copy all of the text of the status page and paste it into the body of your next post here.



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I am a Customer Expert volunteering my time to help other customers here in the Forums.
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Frequent Visitor

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Thanks!

 

When the outage started:

https://imgur.com/aqr7LuW

 

During the outage:

https://imgur.com/WqYDPsg

 

And after refresh:

https://imgur.com/VEeFk2Q

 

 

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Frequent Visitor

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

 

I kept a log from the first week or so of September:

 

DateTimeOutage TypeOutage DetailEvents
9/1/202012:16BlipInternet disconnected, streaming video stopped 
9/1/202012:18BlipInternet disconnected, streaming video stopped 
9/1/202013:03BlipInternet disconnected, streaming video stopped 
9/1/202013:16BlipStreaming video stoppedFront door opened/closed, Small aircraft overhead
9/1/202013:18BlipStreaming video stoppedInternal garage door opened/closed
9/1/202013:50Full OutageInternet down 
9/2/202011:30Full OutageInternet down 
9/2/202013:35SlowPoor video conferencing, audio/video cutting out 
9/2/202012:45Full OutageInternet downDistant helicopter
9/2/202013:12BlipStreaming video stopped 
9/2/202013:25BlipStreaming video stoppedInternal door closed due to wind gust thru window
9/2/202013:28BlipStreaming video stoppedFront door opened/closed
9/2/202013:31BlipStreaming video stoppedFront door opened/closed
9/2/202015:14BlipVideo conference stutter 
9/3/202010:52BlipInternet disconnectedSomeone entered the room
9/3/202012:16BlipInternet disconnected 
9/3/202012:17BlipInternet disconnected 
9/3/202013:08BlipInternet disconnected 
9/3/202013:10BlipInternet disconnected 
9/3/202013:24BlipInternet disconnected 
9/3/202013:29BlipInternet disconnected 
9/3/202013:32BlipInternet disconnected 
9/3/202013:34BlipInternet disconnected 
9/3/202019:56BlipStreaming video stopped 
9/3/202020:04BlipStreaming video stopped 
9/3/202020:24BlipStreaming video stoppedChild walking around house with electronic voice changer
9/4/202011:24BlipOnline meeting video/audio dropped 
9/4/202011:40BlipInternet disconnectedInternal door closed
9/4/202012:20Full OutageInternet down 
9/4/202012:36BlipInternet disconnected 
9/4/202012:37BlipInternet disconnected 
9/4/202013:08BlipStreaming video stopped 
9/4/202013:10Full OutageStreaming video stoppedCoffee machine activated
9/4/202013:24BlipStreaming video stoppedChild walked up stairs
9/4/202013:34BlipStreaming video stopped 
9/4/202015:45BlipInternet disconnectedGardners outside
9/5/202013:31BlipInternet disconnectedCoffee machine activated
9/5/202014:07BlipInternet disconnectedLoud jet
9/6/202013:24Full OutageInternet downMicrowave
9/9/202010:10BlipInternet disconnected 
9/9/202010:13BlipInternet disconnectedGarbage Truck outside
9/9/202010:23BlipInternet disconnectedDistant gardener with mower
9/9/202011:50BlipInternet disconnected 
9/9/202012:38Full OutageInternet downGarbage truck in distance
9/10/202011:30BlipInternet disconnected 
9/10/202011:35BlipInternet disconnected 
9/10/202011:37BlipInternet disconnected 
9/10/202012:08Full OutageInternet down 
9/10/202013:19BlipInternet disconnected 
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Frequent Visitor

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Does anyone think it could be an electical circuit thing? A spike in usage like eg. Microwave or Garage Door or Coffee machine heating? Is there any way I can rule that out?

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Expert

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Something intermittent 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 !



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Official Employee

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Hi @seattlecable1

Thank you for using the Forum to share the experience you've been having with your modem. I agree with @EG. There appears to be something else that could be causing this. I'd be happy to investigate and 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." 


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Frequent Visitor

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Thank you so much @ComcastChe and @EG !

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Expert

Re: Really odd modem problem that happens at a random (but mostly constrained) time of day.

Quite welcome. Good luck !


I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!