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Internet connection intermittently disconnecting throughout day and even overnight.

mscosti3
Regular Visitor

Internet connection intermittently disconnecting throughout day and even overnight.

Hi all. Recently, I want to say around Thursday or Friday of last week, we started noticing that our internet connection has been randomly dropping, and then within 5-10 minutes it connects again just fine, and back to full speeds.  I noticed that when this is observed, our modem visibily resets (lights turn off, and begins start up sequence again), leading me to think there is issue with the modem. 


After this, I did some research on my own to 'catch' the disconnects in the act and get some hard data; I installed an uptime monitor application on my desktop that is connected via ethernet to my router which is connected to my modem, and have been letting that run during the day and overnight. I was also able to pull my modem's logs through the console page, and the time stamps for when I lost connection is also when I got suspect timeout logs and a message saying a restart has happened

 

 

May 12 2020 15:35:45	3-Critical	R05.0	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:35:43	5-Warning	Z00.0	MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 0:00:15	6-Notice	N/A	Cable Modem Reboot due to T4 timeout ;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:34:50	3-Critical	R04.0	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:32:50	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:32:31	3-Critical	R07.0	Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:32:11	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:32:11	3-Critical	R07.0	Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:31:51	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:31:51	3-Critical	R07.0	Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 15:27:35	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:03:27	3-Critical	R05.0	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:03:26	5-Warning	Z00.0	MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 0:00:15	6-Notice	N/A	Cable Modem Reboot due to T4 timeout ;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:02:34	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:02:34	3-Critical	R07.0	Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:02:14	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:02:14	3-Critical	R07.0	Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:01:54	3-Critical	R02.0	No Ranging Response received - T3 time-out;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;
May 12 2020 13:01:54	3-Critical	R07.0	Unicast Ranging Received Abort Response - initializing MAC;CM-MAC=6c:ca:08:89:ae:ec;CMTS-MAC=94:d4:69:54:f5:cc;CM-QOS=1.1;CM-VER=3.0;

 

 

Below are my signal levels from a screen grab around the time I pulled the above logs

modem_signal_5_12.jpg

 

Not being an expert on how to read this data, I first Contacted xfinity customer chat support. We restarted my modem, and was told to contact the modem manufacturer. I did this through Arris support chat, and gave them the similiar data as above (Not exactly the same logs/signal since these were screengrabbed earlier in the day near a reset). 

 

They told me that my power levels for my upstream are looking a little low, and that it needs to be above 45dBmV. At the time of the chat, my minimum was 44, maximum was 45. The screenshot was taken a little earlier, so the levels were slightly higher.

 

Here's a quote from our chat:

(5/12/2020, 7:34:57 PM): We just found the root cause of the intermittent connection.
In first place, It seems like Xfinity is no longer providing internet service with the SB6121 devices, and that might cause some interruptions on your connection.
And also, The Power on the Upstream Channels is not between the acceptable levels (It must be above 45 dBmV) and that´s causing the intermittent connection because when the device detects that it is not reaching the acceptable levels it "Refreshes" the signal, disconnecting everything for a while trying to reach the acceptable levels but it is not going to reach it because the issue is on the signal itself.
In these cases what we recommend is for you to contact your Internet Service Provider to fix the Cable Signal Levels because the Power on the Upstream Channels is not between the acceptable levels. We also recommend to ask for a Tier 2 agent for that. 
Me (5/12/2020, 7:37:43 PM): hmm ok. I just refreshed the page and now its showing 46 min 47 max, but i'm guessing its fluctuating 
Keyner A (5/12/2020, 7:39:24 PM): Exactly, it seems to be inconsistent on the power levels. That may also cause slow speed or as in this case intermittent connection issues. 

 

Just to be ultra clear, I candidly asked if replacing my modem (SB6121) would fix this, and he said ultimately the root cause is with the signal levels, and replacing to something better supported now wouldn't necessarily fix it, and the levels must be addressed first. I'm still getting my speed (and then some, actually) with my current setup when it is functioning.

Me (5/12/2020, 7:46:07 PM): I see, thank you. This is good info to have. Is the problem with the signal likely to persist if I were to say, upgrade the modem? I'm afraid upgrading wouldn't fix the underlying problem. 
Keyner A (5/12/2020, 7:46:47 PM): Yes, exactly! Because the Cable Signal Levels must be between the same ranges for all our devices to properly work. 
Me (5/12/2020, 7:47:30 PM): sorry, so upgrading wouldn't really fix anything, correct? Signal issue must be addressed. 
Keyner A (5/12/2020, 7:48:26 PM): Exactly, Matthew. That's right! 

Does this sound like a sound conclussion? That their is an (new?) issue with our signal connection that is causing our modem to miss behave? 

 

If so, is this something that is possible to be fixed remotely / onsite but outside of our home, or would a tech need to come inside our house in order to resolve ? We're not sure if we're 100% comfortable with that thought due to the current pandemic. 

EG
Expert

Re: Internet connection intermittently disconnecting throughout day and even overnight.

Can't see your pic. Since you are a new poster, it needs to be approved by a Forum Admin. That could take some time. In the interim, you could try hosting it at one of those free third-party pic hosting sites like Imgur or Photobucket and post the link to it here.



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I am a Customer Expert volunteering my time to help other customers here in the Forums.
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mscosti3
Regular Visitor

Re: Internet connection intermittently disconnecting throughout day and even overnight.

It looks like it may be showing up now / been approved.

 

In case you still can't see it here is the image I tried to show yesterday:

https://imgur.com/a/wbzi5Yz

 

I just got another random drop in connection a few moments ago, and took another screenshot of the signal soon after it happened:

https://imgur.com/a/q6Wwy6e

 

Notice that most recently, it only seems to have connected with a single upstream channel (out of 4). This is the first I'm seeing this... I feel like a manual power cycle would fix that but am unable to right now since Its 'working' and need the connection for work at the moment.

 

EDIT: It was getting so bad that I did manually power cycle and it's working again on all 4 channels for now.

 

EG
Expert

Re: Internet connection intermittently disconnecting throughout day and even overnight.

This may not be the direct cause of the problem (YMMV) but the downstream power levels and the SNR's are a bit on the low / marginal side and they may be intermittently even lower to out of spec levels. 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 perhaps it's best to book a tech visit to investigate and correct.



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I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!