Modem disconnecting

Modem: Netgear Nighthawk CM1200

My internet will be fine for about 10-15 minutes then the downstream light will randomly start blinking and cause interruptions in the network. This issue just started today a couple hours ago.

Error logs:

Time Priority Description
Sat Jan 01 21:57:57 2022 Warning (5) DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:57:54 2022 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:55:43 2022 Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:55:20 2022 Notice (6) CM-STATUS message sent. Event Type Code: 4; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:55:17 2022 Notice (6) CM-STATUS message sent. Event Type Code: 22; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:54:54 2022 Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:54:51 2022 Notice (6) CM-STATUS message sent. Event Type Code: 23; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:54:44 2022 Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:54:33 2022 Notice (6) CM-STATUS message sent. Event Type Code: 21; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:54:33 2022 Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:53:55 2022 Notice (6) CM-STATUS message sent. Event Type Code: 20; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:53:55 2022 Notice (6) CM-STATUS message sent. Event Type Code: 1; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:53:55 2022 Warning (5) MDD message timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:53:53 2022 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:51:20 2022 Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:52 2022 Notice (6) CM-STATUS message sent. Event Type Code: 4; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:49 2022 Notice (6) CM-STATUS message sent. Event Type Code: 22; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:33 2022 Notice (6) CM-STATUS message sent. Event Type Code: 1; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:31 2022 Warning (5) MDD message timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:26 2022 Notice (6) CM-STATUS message sent. Event Type Code: 23; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:23 2022 Warning (5) Dynamic Range Window violation
Sat Jan 01 21:50:23 2022 Warning (5) RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:22 2022 Warning (5) DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:16 2022 Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:15 2022 Notice (6) CM-STATUS message sent. Event Type Code: 21; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:13 2022 Notice (6) CM-STATUS message sent. Event Type Code: 23; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:50:12 2022 Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:36 2022 Notice (6) CM-STATUS message sent. Event Type Code: 1; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:36 2022 Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:33 2022 Notice (6) CM-STATUS message sent. Event Type Code: 21; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:31 2022 Warning (5) MDD message timeout;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:27 2022 Notice (6) CM-STATUS message sent. Event Type Code: 5; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:27 2022 Notice (6) CM-STATUS message sent. Event Type Code: 23; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:26 2022 Notice (6) CM-STATUS message sent. Event Type Code: 20; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;
Sat Jan 01 21:49:14 2022 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=REDACTED;CMTS-MAC=REDACTED;CM-QOS=1.1;CM-VER=3.1;

Startup Procedure

Procedure	Status	Comment
Acquire Downstream Channel	627000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Security	Enabled	BPI+
IP Provisioning Mode	Honor MDD	honorMdd(4)

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	37	627000000 Hz	5.6 dBmV	43.3 dB	0	0
2	Locked	QAM256	13	483000000 Hz	1.9 dBmV	43.2 dB	0	0
3	Locked	QAM256	14	489000000 Hz	2 dBmV	43.2 dB	0	0
4	Locked	QAM256	15	495000000 Hz	2.1 dBmV	43.2 dB	0	0
5	Locked	QAM256	16	501000000 Hz	2.2 dBmV	43.2 dB	0	0
6	Locked	QAM256	17	507000000 Hz	2.3 dBmV	43.2 dB	0	0
7	Locked	QAM256	18	513000000 Hz	2.6 dBmV	43.3 dB	0	0
8	Locked	QAM256	19	519000000 Hz	2.9 dBmV	43.4 dB	0	0
9	Locked	QAM256	20	525000000 Hz	3 dBmV	43.2 dB	0	0
10	Locked	QAM256	21	531000000 Hz	3.1 dBmV	43.3 dB	0	0
11	Locked	QAM256	22	537000000 Hz	2.9 dBmV	43.3 dB	0	0
12	Locked	QAM256	23	543000000 Hz	2.6 dBmV	43.2 dB	0	0
13	Locked	QAM256	24	549000000 Hz	2.1 dBmV	43 dB	0	0
14	Locked	QAM256	25	555000000 Hz	1.7 dBmV	42.8 dB	0	0
15	Locked	QAM256	26	561000000 Hz	1.5 dBmV	42.7 dB	0	0
16	Locked	QAM256	27	567000000 Hz	1.3 dBmV	42.6 dB	0	0
17	Locked	QAM256	28	573000000 Hz	1.1 dBmV	42.5 dB	0	0
18	Locked	QAM256	29	579000000 Hz	1.1 dBmV	42.4 dB	0	0
19	Locked	QAM256	30	585000000 Hz	1.2 dBmV	42.4 dB	0	0
20	Locked	QAM256	31	591000000 Hz	1.2 dBmV	42.4 dB	0	0
21	Locked	QAM256	32	597000000 Hz	1.3 dBmV	42.5 dB	0	0
22	Locked	QAM256	33	603000000 Hz	1.5 dBmV	42.5 dB	0	0
23	Locked	QAM256	34	609000000 Hz	1.7 dBmV	42.5 dB	0	0
24	Locked	QAM256	35	615000000 Hz	2.3 dBmV	42.1 dB	0	0
25	Locked	QAM256	36	621000000 Hz	3.5 dBmV	42.8 dB	0	0
26	Locked	QAM256	38	633000000 Hz	5.5 dBmV	43.2 dB	0	0
27	Locked	QAM256	39	639000000 Hz	2.2 dBmV	42.1 dB	0	0
28	Locked	QAM256	40	645000000 Hz	-0.4 dBmV	41.1 dB	0	0
29	Locked	QAM256	41	651000000 Hz	-1.6 dBmV	40.6 dB	0	0
30	Locked	QAM256	42	657000000 Hz	-2.3 dBmV	40.3 dB	0	0
31	Locked	QAM256	43	663000000 Hz	-2.4 dBmV	40.3 dB	1	0
32	Locked	QAM256	44	669000000 Hz	-1.7 dBmV	40.7 dB	0	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	1	5120 Ksym/sec	35600000 Hz	42 dBmV
2	Locked	ATDMA	2	5120 Ksym/sec	29200000 Hz	41.5 dBmV
3	Locked	ATDMA	3	5120 Ksym/sec	22800000 Hz	42.3 dBmV
4	Locked	ATDMA	4	5120 Ksym/sec	16400000 Hz	42 dBmV
5	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
6	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV

Downstream OFDM Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power	SNR / MER	Active Subcarrier Number Range	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Not Locked	0	0	0 Hz	0 dBmV	0.0 dB	0 ~ 4095	0	0	0
2	Not Locked	0	0	0 Hz	0 dBmV	0.0 dB	0 ~ 4095	0	0	0

Upstream OFDMA Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power
1	Not Locked	0	0	0 Hz	0 dBmV
2	Not Locked	0	0	0 Hz	0 dBmV

Responses

Accepted Solution

EG

Expert

•

110.6K Messages

3 years ago

Even though the signal stats looked o/k at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) / an upstream channel-return path impairment somewhere.

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They can check the CMTS (Cable Modem Termination System) for any real time degradation and / or error reports, see your node / cable plant and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

user_bf0543

Visitor

•

4 Messages

@EG Thank you for your assistance.

(edited)

3 years ago

EG

Expert

•

110.6K Messages

@user_bf0543

Quite welcome !!

I am not a Comcast Employee.
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? Please mark an Accepted Answer! tick

3 years ago

user_bf0543

Visitor

•

4 Messages

3 years ago

I have checked the line from the pole as well. The technician that had to come out when we first moved in removed the splitter and installed an attenuator since we only needed one line in the house. Everything worked fine for about a week before these issues arose.

CCHeather

Problem Solver

•

1.1K Messages

@user_bf0543 Thank you for reaching out to the Digital Care Team. I hate to hear this has been your experience and would love to investigate this for you! Please send us a PM with your first and last name, as well as house numbers to your service address. To send us a Private Chat Message, select the message icon in the top right corner and then search for Xfinity support. With our new Xfinity support chat, you do not need to input the name of a person. Just select Xfinity support and you will be able to speak with the next available specialist.

I no longer work for Comcast.

3 years ago

user_bf0543

Visitor

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4 Messages

I have sent a message as directed.

3 years ago

Your Home Network

user_bf0543

Modem disconnecting

EG

user_bf0543

EG

user_bf0543

CCHeather

user_bf0543

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