CM1200 Modem Dropping Connection

Just recently installed the Netgear CM1200 modem to support the 1G Internet service I upgraded to from my ISP "RCN" here in Pennsylvania. I also have an RAX70 Netgear Nighthawk (also new) attached an...

bcooper27

Star

Jan 22, 2021

Lets try this. See attached pdf.

NETGEAR Modem CM1200.pdf67 KB

FURRYe38

Guru - Experienced User

Jan 22, 2021

NOt all your down channels are locked in. For a 1G service you should be getting all 31 or 32 channels lock in. Something to check with the ISP about.

Heres mine:

Startup Procedure

Procedure	Status	Comment
Acquire Downstream Channel	837000000 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	31	837000000 Hz	-2.5 dBmV	37 dB	0	0
2	Locked	QAM256	2	657000000 Hz	-2.4 dBmV	36.5 dB	0	0
3	Locked	QAM256	3	663000000 Hz	-2.2 dBmV	36.6 dB	0	0
4	Locked	QAM256	4	669000000 Hz	-2.1 dBmV	36.6 dB	0	0
5	Locked	QAM256	5	675000000 Hz	-2 dBmV	36.6 dB	0	0
6	Locked	QAM256	6	681000000 Hz	-1.8 dBmV	36.8 dB	0	0
7	Locked	QAM256	7	687000000 Hz	-1.7 dBmV	36.8 dB	0	0
8	Locked	QAM256	8	693000000 Hz	-1.5 dBmV	36.8 dB	0	0
9	Locked	QAM256	9	699000000 Hz	-1.3 dBmV	37 dB	0	0
10	Locked	QAM256	10	705000000 Hz	-1.3 dBmV	36.8 dB	0	0
11	Locked	QAM256	11	711000000 Hz	-1.2 dBmV	36.9 dB	0	0
12	Locked	QAM256	12	717000000 Hz	-0.7 dBmV	37.1 dB	0	0
13	Locked	QAM256	13	723000000 Hz	-0.8 dBmV	36.9 dB	0	0
14	Locked	QAM256	14	729000000 Hz	-0.7 dBmV	36.9 dB	0	0
15	Locked	QAM256	15	735000000 Hz	-0.5 dBmV	37 dB	0	0
16	Locked	QAM256	16	741000000 Hz	-0.5 dBmV	37.1 dB	0	0
17	Locked	QAM256	17	753000000 Hz	-0.6 dBmV	37.1 dB	0	0
18	Locked	QAM256	18	759000000 Hz	-0.8 dBmV	37.1 dB	0	0
19	Locked	QAM256	19	765000000 Hz	-1.2 dBmV	37.1 dB	0	0
20	Locked	QAM256	20	771000000 Hz	-1.2 dBmV	37.2 dB	0	0
21	Locked	QAM256	21	777000000 Hz	-1.4 dBmV	37.3 dB	0	0
22	Locked	QAM256	22	783000000 Hz	-1.6 dBmV	37.3 dB	0	0
23	Locked	QAM256	23	789000000 Hz	-1.7 dBmV	37.3 dB	0	0
24	Locked	QAM256	24	795000000 Hz	-1.8 dBmV	37.3 dB	0	0
25	Locked	QAM256	25	801000000 Hz	-2 dBmV	37.1 dB	0	0
26	Locked	QAM256	26	807000000 Hz	-2 dBmV	37.2 dB	0	0
27	Locked	QAM256	27	813000000 Hz	-2.1 dBmV	37.2 dB	0	0
28	Locked	QAM256	28	819000000 Hz	-2.5 dBmV	37 dB	0	0
29	Locked	QAM256	29	825000000 Hz	-2.3 dBmV	37.2 dB	0	0
30	Locked	QAM256	30	831000000 Hz	-2.4 dBmV	37 dB	0	0
31	Locked	QAM256	32	843000000 Hz	-2.5 dBmV	37 dB	0	0
32	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 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	36000000 Hz	39 dBmV
2	Locked	ATDMA	2	5120 Ksym/sec	29000000 Hz	37.8 dBmV
3	Locked	ATDMA	5	5120 Ksym/sec	22000000 Hz	38.3 dBmV
4	Locked	ATDMA	6	2560 Ksym/sec	16000000 Hz	37 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	Locked	0 ,1 ,2	33	547000000 Hz	-4.0 dBmV	36.6 dB	1108 ~ 2987	713286238	549483486	9
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

bcooper27
Star
Jan 23, 2021
My ISP RCN tech told me tonight in the 2-3 years he’s handled troubleshooting 1G service he’s only ever seen 16-channels locked. He thinks it’s an issue with the equipment itself. He saw no drop issues overnight when I lost service so he thinks possible bad modem.
- plemans
  Guru - Experienced User
  Jan 23, 2021
  But you've also only got 2 locked upload. it could be a bad unit. Nothing is saying it isn't but my channels lock the same as FURRYe38 and I'm on a 1 gig line.
- FURRYe38
  Guru - Experienced User
  Jan 23, 2021
  I would presume this tech should know that for any 1Gb service, at least here in the US region, 32 is the norm for this speed service. If there not seeing anything liek this, there it's either there signal that needs to be check into or of course could be bad modem HW. I beleive the DOCSIS spec uses 31-32 channels for 1G service lines. Unless some ISP has figured out how to compress a 1Gb service line to 16 channels...would be doubtful though....
  
  Try another modem and see if the problem follows or not.
  bcooper27 wrote:
  My ISP RCN tech told me tonight in the 2-3 years he’s handled troubleshooting 1G service he’s only ever seen 16-channels locked. He thinks it’s an issue with the equipment itself. He saw no drop issues overnight when I lost service so he thinks possible bad modem.
  - bcooper27
    Star
    Jan 23, 2021
    I chatted with another RCN rep who insisted everything was fine. I told them I wanted it escalated to their tech group to have this looked at and they said I’ll get an answer in a few days. I have a Nighthawk AX8 RAX70 attached to the modem and my speed tests do hit 850-890Mbps. Still think something is wrong here considering everyone’s responses. I’ll get to the bottom of it.

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CM1200 Modem Dropping Connection