Visitor
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8 Messages
Intermittent Internet access problems
Ever getting Xfinity cable internet at my new house, I've had this problem.
Every day, my internet connection drops for a few minutes. This happens multiple times per day.
I work from home and it is such a problem that I signed up with a second ISP, using DSL for my work connection, since I can't just disappear from Zoom meetings.
I thought maybe the problem was the Xfinity modem, so I bought my own, a Motorola MB8611. The problem remained the same.
The problem is the same regardless of whether I connect the modem to my wifi router or directly to a computer.
This problem does not occur when I'm connected to my DSL ISP. I am confident it has nothing to do with my network or computers.
I tried calling Xfinity support. However, they have a hard time understanding the nature of the problem. I tell them that it is intermittent, and I need someone to look at my line. They want me to reboot my computer, my router. They ask me if it is working now. "Yes, it is working now. The problem is that sometimes it stops working."
"So it's fixed now?" they ask.
I'd like to talk to someone that can look at my modem event log and my modem status and help me figure out what is going on.
Accepted Solution
BruceW
Gold Problem Solver
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26.2K Messages
3 years ago
The signals you posted show out of spec downstream power, SNR, and excessive error counts on many channels. Network connection problems like this are often due to poor coax connections or damaged coax cable, usually in or near your home. Modems can fail of course, but that happens much less often.
Yes, MAC addresses are considered "personal information" by Forum security procedures, but there's really no need to post the event log, given the terrible downstream signals.
If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you can't find the problem lean on Comcast hard to send a tech out to identify the cause and correct it. It's not likely they can fix the problem remotely.
If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit ($70-$100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
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user_dfc320
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8 Messages
3 years ago
I posted a log but it got removed, I assume because it had MAC addresses in it. I have now edited the screen shot to block out the MAC addresses, I can post that, maybe?
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user_dfc320
Visitor
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8 Messages
3 years ago
BruceW thanks for your response. It was very helpful. After reading through the troubleshooting page you linked, I've concluded that my intermittent outages are very likely "no block syncs" which reset my modem.
My internal cabling looks ok so I hunted around the outside of the house and spotted a splitter that looks like it's seen better days. I bypassed it with a coupler and the resulting SNR's are higher, though if I read the status correctly I still have at least one channel that's out of spec (channel 22). This status is after about 20 minutes of rebooting the modem and while I like the large number of zeroes (thus far), the number of uncorrectables on a few channels still seems to be pretty high.
This weekend I'll probably get a power extension cable and park my modem directly on that input coax outside the house, to see if there is a difference in the signal. This will help determine if the problem is internal wiring, I think. If the signals are the same, I think I then have a very good case for a problem in the wire coming to my house.
Thanks again for the help.
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BruceW
Gold Problem Solver
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26.2K Messages
3 years ago
Those are some solid troubleshooting ideas, well done! The new stats look pretty good, except for the weirdness around 633 MHz as you noted. I'm not sure what to make of that. I'm gonna guess Comcast may have placed an old-school "channel trap" on your drop at some time in the past, but that's just a guess.
Please keep us posted here, and good luck!
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user_dfc320
Visitor
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8 Messages
3 years ago
All righty. I could not do my testing last weekend because we had to prepare for houseguests. This weekend, though, I spent it pretty sweaty and dusty tracing cables, lifting ceiling tiles, trawling through the nooks and crannies of my house trying to isolate where errors might be coming from, if in-home cabling is causing it.
To make a long story short, eventually I found the dingus in the picture I am posting: some kind of powered splitter. First I bypassed it to test the cable going upstairs (pictured here).
Then I bypassed it, using the "input" cable directly into my cable modem, and what do you know, the signal was pretty clean (though not perfect).
So I still have a little troubleshooting to do, seeing which of the various cable outputs from this thing can be used to park a modem in my house where it makes some sense. But for now I think we can say that we've found the biggest contributor to the problem: one of the cables running from a powered splitter.
Thanks to everyone who responded. It was extremely helpful to get some feedback from folks that could read the logs and status.
To the Xfinity folks monitoring this thread, thanks for your participation. It would be good if you could provide feedback to your support management that maybe phone support folks could be provided a way to receive and look at screenshots to help them guide customers through further troubleshooting. I spent a long long time putting up with bad connections because I didn't know I could skip phone support and come to forums.
Not trying to disrespect the phone folks...resetting the modem sometimes helps. It's just a little frustrating when it seems that's all that phone support folks do, if you don't know there are other options.
Anyway, thanks a bunch!
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user_dfc320
Visitor
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8 Messages
3 years ago
I posted a followup but it seems to be marked "private". Does this mean other people can't see it?
It doesn't have any private information so I'm not sure.
I explain some additional troubleshooting I did above ceiling tiles. Can you guys see it?
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BruceW
Gold Problem Solver
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26.2K Messages
3 years ago
We couldn't see it last night, but it's visible now. The Forum makes all posts containing images private automatically, in an overreaction to a handful of inappropriate pics that were posted over the years. Forum Administrator @XfinityJessie has posted:
See https://forums.xfinity.com/conversations/getting-started/disappearing-forum-posts/606894c37437b81d05b7b638?commentId=606b25cb322c887da0f3c0a2
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Is the splitter getting power? One of the coax cables should be connected to a power pack somewhere.
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user_dfc320
Visitor
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8 Messages
3 years ago
BruceW: yes this is what raised my curiosity, actually. I was poking around looking for cables and spotted an out-of-the-way outlet that had an adaptor and a coax cable coming out of it. I traced that cable to the splitter and it's connected to the power input, so I think the splitter is powered.
I do think this splitter is partly to blame, though the cable I bypassed was a much more serious culprit.
Using the splitter I'm still getting a lot of correctable errors, so at some point this week when my family and houseguests can handle the network downtime, I'll probably get back up there and bypass the splitter entirely with a coupler. I only need one cable drop in the house, as we only have one modem and we don't subscribe to TV service.
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