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random outages and slower speeds

Regular Visitor

random outages and slower speeds

I've been having this issue since I started my service with comcast. Internet would cut out for a couple minutes to a couple hours with yesterday (5/11/18) being the worst at 8+ hours down. Other days I get speeds from 80-0.5mb download while upload seems for the most part unaffected. The issue started with my Netgear CM700 modem then I switched to Netgear CM1000 and the issue persisted. Reading Netgear forums it looks like netgear mods and users are blaming comcast.


Modem has all lights lit up and it never changes even when internet goes down. Plugging directly into modem does not work other than give random short times where internet pops back up but at 2mb speeds and goes down again. 

Speed tests attached are from today


Imgur post the pictures of modem logs with either non working or working. All non working logs were taken from 5/11/18 and working from 5/12/18. This is the second modem and I even have a third Arris SB6141 that I would like to return but can be used to test. (Current modem is CM1000)


I have called tech support numerous times (7-8 times) and nobody has fixed the issue while one told me that the modem is at fault.



Google speed test.PNG
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Diamond Problem Solver

Re: random outages and slower speeds

All of the modems signal stats are badly borked ! That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.


Re: random outages and slower speeds



I've asked a Comcast employee to help you. You should expect a reply in this thread. 


If you would like to do some troubleshooting on your own see the troubleshooting guide

I am a volunteer Expert/Moderator, not an employee.

Official Employee

Re: random outages and slower speeds

Hello Molybdenum. I can assist with further troubleshooting your internet connectivity issues. I'd like to start with polling the CMTS for real-time and historical RF signal reports from your modem. I can also check your local Node/Plant for any degradation or error reports. Please send me a private message and include your full name and account primary phone number so I can access your equipment.