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SB6121 Poor Internet performance

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SB6121 Poor Internet performance

My internet has been incredibly flakey (dropped packets and slow speed) for the past couple months.

I own my own SB6121 modem

Here are the stats from the admin portal

comcast.png

A reboot of the modem normaly clears up the issue for a couple hours.   I am not familiar with the stats on this page to pin point an issue.

 

This is what I see in the logs as well.

Time Priority Code Message
Feb 16 2018 11:50:35 6-Notice N/A MDD Recovery following MDD Loss;CM-MAC=a4:7a:a4:73:3a:bf;CMTS-MAC=00:01:5c:87:0e:4f;CM-QOS=1.1;CM-VER=3.0;
Feb 16 2018 11:47:38 5-Warning T202.0 Lost MDD Timeout;CM-MAC=a4:7a:a4:73:3a:bf;CMTS-MAC=00:01:5c:87:0e:4f;CM-QOS=1.1;CM-VER=3.0;
Feb 16 2018 11:47:38 5-Warning N/A DS Partial Service Fallback: MDD Lost-> CM in DOCSIS 3.0 Recovery Mode ;CM-MAC=a4:7a:a4:73:3a:bf;CMTS-MAC=00:01:5c:87:0e:4f;CM-QOS=1.1;CM-VER=3.0;
Feb 16 2018 11:47:13 6-Notice N/A MDD Recovery following MDD Loss;CM-MAC=a4:7a:a4:73:3a:bf;CMTS-MAC=00:01:5c:87:0e:4f;CM-QOS=1.1;CM-VER=3.0;
Feb 16 2018 11:46:44 5-Warning T202.0 Lost MDD Timeout;CM-MAC=a4:7a:a4:73:3a:bf;CMTS-MAC=00:01:5c:87:0e:4f;CM-QOS=1.1;CM-VER=3.0;
Feb 16 2018 11:46:44 5-Warning N/A DS Partial Service Fallback: MDD Lost-> CM in DOCSIS 3.0 Recovery Mode ;CM-MAC=a4:7a:a4:73:3a:bf;CMTS-MAC=00:01:5c:87:0e:4f;CM-QOS=1.1;CM-VER=3.0;
Diamond Problem Solver

Re: SB6121 Poor Internet performance

The SNR is too low / out of spec on channel 6. And the upstream power is borderline / too high and may be intermittently fluctuating even higher out of spec. 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.


Admin1

Re: SB6121 Poor Internet performance

Hi iliketrails -- The information provided by EG is excellent and very helpful when trying to resolve this issue on your own. We would recommend an on-site tech visit if you're unable to resolve this problem yourself. We can help get that scheduled for you. Can you let us know if you need a job setup or if you were able to get this resolved please?