Frequent Visitor
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10 Messages
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
Responses
seattlecable1
Frequent Visitor
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10 Messages
6 m ago
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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seattlecable1
Frequent Visitor
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10 Messages
6 m ago
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)
Then, a few moments later, I refreshed the page and saw this:
(2 bonded channels)
Before it returned to this again:
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EG
Expert
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86.5K Messages
6 m ago
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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seattlecable1
Frequent Visitor
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10 Messages
6 m ago
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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seattlecable1
Frequent Visitor
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10 Messages
6 m ago
I kept a log from the first week or so of September:
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seattlecable1
Frequent Visitor
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10 Messages
6 m ago
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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EG
Expert
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86.5K Messages
6 m ago
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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ComcastChe
Official Employee
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6.1K Messages
6 m ago
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."
Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. 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!
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seattlecable1
Frequent Visitor
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10 Messages
6 m ago
Thank you so much @ComcastChe and @EG !
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EG
Expert
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86.5K Messages
6 m ago
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