04-12-2012 02:06 AM
For the past several months, my internet has had intermittent connectivity issues. Everything will be working fine, and all of the sudden I will lock up in any online game I'm playing, websites will stop loading, etc.
The first tech that came out replaced something on the pole coming to my house, because he said my upstream power was too high (it was, at the time it was 56+, it has remained at 50 or below since his visit). It worked flawlessly for a short while afterward. After a week or two I began having issues again, so I put in another service request. The second tech was here for quite a while, checked out a lot of stuff, and ended up replacing the line coming from the pole to my house. Again, after he left everything looked great, and I had no issues for a week or two.
I have been watching my modem diagnostics very closely so I can try to be as informative as I can, because I want to get this resolved. From what I have noticed watching my diagnostics, typically my highest numbered downstream channel (id'ed as 7 or 8) is the one with issues. Everything will look fine, power levels in the 1-5 range, snr of 34-36+, then the power level will jump up or down to + or - 10, snr will drop to below 29 and the channel will constantly drop in and out of sync for however long it wants to. During all of this my upstream power level remains constant in the 48-50 range. I'm not sure if it's relevant, but during this period of the channel constantly dropping sync, the "uncorrectable codeword" count will skyrocket, As I type this, my modem has the count at 195,252,035 uncorrectable codewords, and 39,279,375 correctable codewords for that channel. I'm sure that can't be a good thing.
Here is the information requested in the sticky thread, tracert and ping taken when I am having issues:
Tracing route to www.l.google.com [184.108.40.206]
over a maximum of 30 hops:
1 1 ms 1 ms <1 ms router.belkin [192.168.2.1]
2 * 625 ms 48 ms c-24-127-246-1.hsd1.fl.comcast.net [220.127.116.11
3 15 ms 10 ms 18 ms te-0-7-0-1-sur01.chaffee.fl.jacksvil.comcast.net
4 * * 13 ms te-0-0-0-3-ar02.southside.fl.jacksvil.comcast.ne
5 29 ms 18 ms 18 ms te-1-1-0-1-cr01.denver.co.ibone.comcast.net [68.
6 42 ms 30 ms * pos-1-12-0-0-cr01.atlanta.ga.ibone.comcast.net [
7 30 ms 30 ms 36 ms pos-0-2-0-0-pe01.56marietta.ga.ibone.comcast.net
8 157 ms 159 ms 164 ms 18.104.22.168
9 42 ms 40 ms 40 ms 22.214.171.124
10 42 ms 42 ms 42 ms 126.96.36.199
11 46 ms 42 ms 43 ms 188.8.131.52
12 * * * Request timed out.
13 47 ms 43 ms 42 ms vb-in-f147.1e100.net [184.108.40.206]
Ping statistics for 220.127.116.11:
Packets: Sent = 150, Received = 131, Lost = 19 (12% loss),
Approximate round trip times in milli-seconds:
Minimum = 41ms, Maximum = 186ms, Average = 47ms
Pic of my downstream modem diagnostics as of this post: http://minus.com/mFiAnIfWh/1f
Pic of my downstream modem diagnostics when I am having issues: http://minus.com/mFiAnIfWh/2f
Pic of upstream modem diagnostics (these pretty much never change): http://minus.com/mFiAnIfWh/3f
I just want to get some opinions on what the issue could be before I schedule another service call. I've tried just about everything I can do on my end outside of having Comcast exchange the modem. Is that something I should try? This doesn't scream modem issue to me but I'm no professional. Any assistance would be much appreciated.
04-12-2012 10:31 AM - edited 04-12-2012 10:32 AM
Are you renting the modem from them ? If so, the tech should have tried swapping it already to rule it out as the cause of the issue. Has it been properly powercycled or reset to defaults in order for it to try obtaining a different downstream channel ? This is more likely to be a problem in the plant/lines or the headend. The premise tech/s should escalate this to the maintenance dept.
04-12-2012 12:11 PM
Yes, I am renting the modem. I have power cycled it several times and it always seems to choose the same channel again and does not change anything. How can I go about having this escalated to the maintenance department if replacing the modem does not resolve the issue?
04-12-2012 12:22 PM - edited 04-12-2012 12:23 PM
So was the modem swapped ? As I stated, it is the premise facing techs who are the ones responsible for escalating an issue that they can't fix/find to the line/maintenance dept. techs.
04-12-2012 12:36 PM
No it was not, sorry for not clarifying. So, I take it my best course of action as of now is to have my modem swapped out then schedule another appointment with a tech if that does not resolve the issue?
04-12-2012 12:52 PM
Yeppers. If you need to you should politely ask the tech to put in a ticket for the maint. dept. even though he knows that that is part of his job if he can't solve your issue.
04-12-2012 01:01 PM
Yeah, it's just kind of a pain because both times techs have came out it's been working fine so I'm sure they can't tell for sure if they have fixed the issue or not. I'll try to get the modem swapped out soon and see how things go. Thanks much for the assistance EG, I appreciate it.
04-13-2012 11:52 AM
It sounds as if there is a downstream frequency issue on channel 7 and 8 this is a common issue if you have bad cable either in the home or in the plant itself I worked on issues like this for years with comcast. now that the cable companys are bonding the DS/US 8x4 256QAM and 64QAM if there are any really big fluctuations in the signal it will degrade service.
more than likely a maintenance technician will only be able to fix this issue they are better equipped in finding these issues
I would make sure the service tech takes a full downstream spectrum scan of the frequenceies to see if there is a roll off or any dips in the scan that will tell alot about the quality of the signal
04-13-2012 11:56 AM - edited 04-13-2012 11:59 AM
I just looked at your pics your DS-4 is in the dirt 27MER is unacceptable spec is 34 and ablve you should be seeing close to 40 MER I would demand a maintenance tech to help resolve this issue
also swapping the modem is usless
04-13-2012 11:59 AM - edited 04-13-2012 12:02 PM
"also swapping the modem is usless"
That can't be known for certain by anyone unless they are omnipotent....
04-13-2012 12:45 PM
04-13-2012 01:34 PM
I never said that it was "bad" but there is always the possibility of a hardware issue with the measuring mechanism. Stranger things have happened, ya' never know.. I kind of agree though.
05-19-2012 01:43 PM
Ok, updating this. Since my initial posting I have had my modem swapped out, that did not help. I had another tech come out last weekend and, as usual with intermittent problems, it was working flawlessly while he was here. The tech had just came from a neighbor around the corner who is experiencing the same thing, by the way. He checked signals coming in from the pole, then checked them at my modem and couldn't find anything wrong. He said there's really not a whole lot he can do if it's working fine. I showed him some of the pics of my signal levels I took and he said it was very unusual for the downstream power to go up like that while the SNR goes down. I asked him about escalating it to the maintenance department, he said that technically he could do that but once the maintenance guys see the ticket and that he couldn't find anything wrong at all, they would just close it. Sounds like a great system they have going!
As of right now my connection has been almost unuseable for the past 4 hours. It is still the same exact problem I documented in my original post. The symptoms and signal level changes are the same as always. My downstream power will shoot up to anywhere from 6-14 dBmV, RxMER drops from 34-35 all the way down to 19-30, uncorrectable codeword count skyrockets, the higher numbered channels will intermittently lose and regain sync, and modulation/interleave depth will randomly change value. I am really at a loss as to what I can do now. The problem is extremely intermittent and this is getting very frustrating. What are my options at this point?
05-19-2012 02:06 PM
To get help, you can contact Comcast Corporate Customer Service (firstname.lastname@example.org) Send a link to this thread and your account details. You can also ask for help in the Broadband Reports Comcast Direct Forum or via Twitter. They can motivate your local system to fix the problem.
Connection and trouble shooting tips (How to check signal levels.) . Info you should post to get help.
The opinions expressed here are my own and are not sanctioned by my employer.
09-14-2012 02:42 PM
It could help a lot to have a log of exactly when and for how long the connection is down. A program like Net Uptime Monitor will continously test your connection and record the outages in a text file. This can help identify the source of the problem or at least prove that the problem is real. Showing a log of outages to Comcast can really inspire them to get serious!
09-14-2012 09:55 PM
I had the same problem as you and perhaps I still do but my connectivity has been very consistent for over 72hours. Whereas, previously my ping almost always fluxuate 50-100ms even when it didn't necessarily timeout. I also had the timeout issues.
I downgraded my cable modem from a DOCSIS 3 to a DOCSIS 2. I'm not exactly sure if it's the reason yet but so far so good.
I think it works like this: DOCSIS 3 has four channels of downstream compared to only one with the DOCSIS 2. I think I fixed my problem because I removed the unneccessary channels and maybe one of those channels had interference. Now it seems like the one channel I'm using is steady.
If you have a higher cable package you wont able to maximize your downstream. But if you're like me with the lowest package it wont affect you. Compare your current speed package to the tables at wikipedia. It's 42.88 (38) Mbit/s per channel. http://en.wikipedia.org/wiki/DOCSIS#Speed_tables
So far my ping has been very consistent and now fluccuates only 3-5ms and I haven't had the timeout problem for 72 hours. Hope that helps.
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