For the past 2 weeks I have had random moments where my internet just stops working. It usually happens for 15-30 minutes at a time and can happen anywhere from once a day to 5 or more times a day.
When it happens my router is no longer able to communicate and sees the connection between the modem and itself as down.
When it comes back up I am able to see the logs and I see during that time all these critical notices for No Ranging Responses Received. I called support one day when it lasted a lot longer than normal and since they couldnt reach my modem they opted to just get a tech out here.
The tech checked the lines and what not and everything he saw looked good. He wanted to reset my router and eventually reset it to factory defaults. I have a AC-5300 and with all the new firmware updates it can take some time to reboot. His diagnosis was the router must be at fault as sometimes it was taking a bit longer to come up and normal. It always came back up in the end and the logs on it indicate no issues at all.
Really interested in seeing if someone here can get a comcast engineer to look at the VCMTS logs and stats to determine if the problem is there or some other potential noise in the line.
One final note I own both my router and my modem the modem is a Netgear CM1000 if it makes a difference.
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What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1
Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.
|<tabindex=-1>Downstream Bonded Channels</tabindex=-1>|
|<tabindex=-1>Upstream Bonded Channels</tabindex=-1>|
|<tabindex=-1>Downstream OFDM Channels</tabindex=-1>|
|<tabindex=-1>Upstream OFDMA Channels</tabindex=-1>|
The upstream power is too high and it may be intermittently fluctuating even farther out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, 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 it's best to get the techs re-involved until it is fixed properly. Good luck !!
My current connection is using a splitter per your specs (one installed by the comcast installation expert). Its currently connected directly from the street and splits off as you suggested should be done.
I will clean up the cables and order a replacement splitter to see if perhaps that fixes it otherwise I guess its time to get the techs back out here again...
I looked online and according so several sites because I am a multi-channel ATDMA the power should be
|Three or more||TDMA||1280 Ksym/sec||+55 dBmV||45 dBmV|
|ATDMA||2560 Ksym/sec||+52 dBmV||45 dBmV|
|5120 Ksym/sec||+51 dBmV||45 dBmV|
I am within these ranges so I am a bit confused on what you believe the power level should be for the upstream? Also isnt this something they could configure on the modem directly similar to wifi signal power?
Thanks for the help I will give it another go or two for now.
The Comcast plant / engineering specs are the only ones that matter. Not something found on the internet... From the Troubleshooting Tips sticky topic at the top of this board;
|Downstream Power Level|
|Gateways and EMTAs||-7dBmV||+7dBmV|
|Downstream Signal to Noise Ratio||35dB||-|
|Upstream Power Level||+35dBmV||+50dBmV|
|Upstream Signal to Noise Ratio||31dB||-|
|Upstream Receive Power||-2dBmV||+2dBmV|
And I guess that you overlooked the part that I stated about "may be intermittently fluctuating higher out of spec" (many readers do) ? Wiggle room is always needed !
As stated, if you can't get it to be any better, get a tech out to investigate / correct it. Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.
Good luck with it !
Thanks to @EG ,
After upgrading to 1Gbps internet since June 2020. Been smooth for a few months, with occational internet drops, that required reboot the CM1200 Netgear modem. Started with once a month, then once a week, to last weeks (Dec. 2020) twice to 3 times a day. Finally started troubleshooting by looking at logs 192.168.100.1 signals and lots of searches to find signal problems. This thread where the upstream power is too high (50-50.3 dBmv) and near the spec boundries seems to be off for my signals (besides for some reason my modem only locks to 9 downstream bonded channels from 543000000 most of the time). After reroute cable directly to cable box, removing 1 unnecessary spliter, and hook up cable modem to only 1 spliter at the -3.5dB output. The upstream power is now down to 41.3~41.5 dBmv). All channels has 0 correctable and 0 uncorrectable packages before and after this cable reroute, also download speed with wired internet is around 940mbps (when its working.)
Will continue to monitor and see if any drop occurs. I also tried to view the modem after an hour live online, seems to connect more downstream channels at higher frequencies. 603-675000000hz. I don't have any clue if this has any impact as when i started troubleshooting it only had 9 channels from 543-597000000. For some reason frequency 483-531000000 never locks.
thanks again for this great spec. on the upstream bonding channel signal power!
Quite welcome ! Glad you got it figured out ! 9 month old dead thread now being closed.