CM1200 losing speed right after reboot

[hubbles_law]

Background - about 48 hours ago, I noticed my internet slow down and struggling. Since then whenever I run a speed test I wind up with ~30Mbps Down | ~20Mbps Up and should be around 1Gbps Down, I called up RCN.

I moved the modem closer to the wall and tested it hardlined to the computer.  I performed countless reboots and a few factory resets.  While looking over http://il.speedtest.rcn.net/merlin/ - I see:

The modem is operating in Partial mode. This may negatively impact service and could indicate a problem with one or more Upstream or Downstream channels.

Last Connection Status: Partially operational

OFDM impairment. Channel disabled by modem.

I only see 20 of 32 Down Channels locked, and on the event log under 192.168.100.1 I have noticed event code 20 and 22 seem to populate regularly.

NOW - the strange part.  Whenever I reboot the modem, after it connects to the internet I can run a speed test and will see around 1Gbps down for the first minute or so if I run multiple tests back to back.  But then it starts to drop and eventually settles back around ~30Mbps... I can recreate this behavior multiple times but the slow down doesn't seem to happen at the same intervals, at least not from what I can tell.

I just spent 4 hours with the service tech who checked all the lines, decided to replace the line to the house, and told me they are seeing everything from their end working just fine. After they did so I am seeing better power but the problem persists for my Netgear CM1200. They even tested their Hiltron CODA-5712 which seemed to be steady for around 15m with 1Gbps down speeds. So my ISP is saying its a problem with my modem.

Which is on firmware V3.02.01 which should be what they are using.

Has anyone seen anything like this? Is my 2 year old modem hardware failing?

[FURRYe38]

Please post a copy and paste of the modems connection status and event log page.
https://kb.netgear.com/30007/How-do-I-obtain-the-cable-connection-information-from-a-NETGEAR-cable-m...
https://kb.netgear.com/30008/How-do-I-view-or-clear-the-event-logs-on-my-NETGEAR-cable-modem-or-mode...

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 
What is the brand and model of the host wifi router connected to the modem?

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html

[hubbles_law]

Thanks for the reply, here are the details:

Enable Extended Upstream Transmit Power is Unchecked

Ethernet Port Aggregation is DISABLED

Startup Procedure

Procedure Status Comment Acquire Downstream Channel 603000000 Hz Locked Connectivity State OK Operational Boot State OK Operational Security Enabled BPI+ IP Provisioning Mode Honor MDD honorMdd(4)

Downstream Bonded Channels (Partial Service)

Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 15 603000000 Hz 1.6 dBmV 39.4 dB 0 0 2 Locked QAM256 1 519000000 Hz 1.6 dBmV 39.7 dB 0 0 3 Locked QAM256 2 525000000 Hz 1.6 dBmV 39.6 dB 0 0 4 Locked QAM256 3 531000000 Hz 1.7 dBmV 39.6 dB 0 0 5 Locked QAM256 4 537000000 Hz 1.8 dBmV 39.7 dB 0 0 6 Locked QAM256 5 543000000 Hz 1.6 dBmV 39.7 dB 0 0 7 Locked QAM256 6 549000000 Hz 1.5 dBmV 39.7 dB 0 0 8 Locked QAM256 7 555000000 Hz 1.2 dBmV 39.6 dB 0 0 9 Locked QAM256 8 561000000 Hz 1.5 dBmV 38.9 dB 0 0 10 Locked QAM256 9 567000000 Hz 1.1 dBmV 39.5 dB 0 0 11 Locked QAM256 10 573000000 Hz 1.1 dBmV 39.1 dB 0 0 12 Locked QAM256 11 579000000 Hz 1.4 dBmV 39.5 dB 0 0 13 Locked QAM256 12 585000000 Hz 1.1 dBmV 39.4 dB 0 0 14 Locked QAM256 13 591000000 Hz 1.3 dBmV 39.4 dB 0 0 15 Locked QAM256 14 597000000 Hz 1.6 dBmV 39.5 dB 0 0 16 Locked QAM256 16 609000000 Hz 1.2 dBmV 39.3 dB 0 0 17 Locked QAM256 17 495000000 Hz 0.6 dBmV 39.6 dB 0 0 18 Locked QAM256 18 501000000 Hz 0.6 dBmV 39.5 dB 0 0 19 Locked QAM256 19 507000000 Hz 1 dBmV 39.5 dB 0 0 20 Locked QAM256 20 513000000 Hz 1.2 dBmV 39.6 dB 0 0 21 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 22 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 23 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 24 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 25 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 26 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 27 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 28 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 29 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 30 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0 31 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 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 36800000 Hz 50.5 dBmV 2 Locked ATDMA 2 5120 Ksym/sec 30350000 Hz 50.8 dBmV 3 Locked ATDMA 3 5120 Ksym/sec 23900000 Hz 50.8 dBmV 4 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 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

Time	Priority	Description
Thu Dec 15 01:13:13 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=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:12:09 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=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:12:07 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=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:56 2022	Warning (5)	REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:53 2022	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:49 2022	Notice (6)	TLV-11 - unrecognized OID;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.9;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.8;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.7;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.6;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.5;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.4;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.3;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.2;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:48 2022	Error (4)	Missing BP Configuration Setting TLV Type: 17.1;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Thu Dec 15 01:11:47 2022	Warning (5)	DHCP WARNING - Non-critical field invalid in response ;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv4
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:ca:e5:c8:c8:ea;CM-QOS=1.1;CM-VER=3.1;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=08:36:c9:a0:db:28;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

[FURRYe38]

You have lots of errors and criticals that the ISP needs to review and resolve. 

Be sure to have them check the other suggestions as well. 

[hubbles_law]

I'll reach back to them with the details on the errors.

Are you able to expand or link me to more information about:

"Be sure the ISP provisions the modem correctly."

I've been reading that the bootfile which is controlled by my ISP could be an issue if they recently changed my plan but I'm not finding much research on what that entails.

[FURRYe38]

That's exactly what some of the config file is...sets speed to what you pay for and also has FW information as well that ISP are responsible for as well. I presume there are other items involved there as well. The ISP will have all this and should have all this information. Seen some ISP not send the config file down to users modems thus causing problems. Then sending down the right one resolves. Just something to have them check into. 

[hubbles_law]

I called them up and started asking the questions about their configuration and boot files, but they told me it was all an automated process they had zero control over.  They just set the speed I am supposed to get and the system does the rest when they provision a modem.

I found my old CM500 modem lying around, and knowing it was in working order when I last upgraded, I had them switch me over to it.  It is getting 400-500 Mbps and working just fine.  I'd like to have access to the full 1GB and am still not convinced there is anything wrong with my CM1200.  It still works, but I don't know if a hardware failure could allow it to start at 1Gbps and then go down to 30Mbps and stay there.  it just doesn't make sense that it wouldn't be the firmware or some other messed up setting.

I'm open to any other ideas if there are any other troubleshooting steps I can take on the CM1200, but from here it's starting to look like they are going to force me to buying a different modem capable of DOCSIS 3.1.

I figure after the holidays I can try my CM1200 again and see if I can complain my way into some decent customer service with someone who may understand the technology enough to try something else on their end.

We really are at the complete mercy of our ISP's.

[FURRYe38]

Ya the CM500 won't support 1Gb. 

Do you have any friends, or family members that you can take the CM1200 too and test there to see if the problem follows or not? 

[Kitsap]

Just an out of the box comment.  Make certain your coax shield has a good connection to ground where it enters your home.  If not, the coax can support a gradual build up of a capacitive charge that impacts signal transmission.  Occasionally the work boundary between home technicians and line technicians obscures this item.