Forum Discussion

Aspirant

Jan 06, 2023

CM2050V - Internet keeps dropping. ISP has no clue.

At my wits end. Internet keeps dropping at cabel modem level (not just wi-fi/router). ISP came out and said it was the ISP provided modem that had issues with the "flaps" and offered to replace it wit...

AzzySpazbourne

Aspirant

Jan 06, 2023

Thanks! Yes, I noticed the big variance in power and boarderline concerning varience in SNR across the 32 downstream bonded channels. Now more and more channels are showing correctible and uncorrectible codes as time goes on, until I end up doing a power cycle or reboot.

LAN cable from modem to main gateway router cable is unlabled, so cannot verify that it is CAT6A STP, but I assume it is as it is the one that came with the router system. Router being used is eero 6 Pro mesh (1 as wired gateway with 2 others as wirelesh mesh extenders).

When ISP techvwas out here last week, he checked the wiring and said it all looked good, and when we swapped out the old modem for this model, everything was great and all stats were within range. If other writing issues, would it take 7 days to show up without dropping issues? Just want to know what to do or advocate/ask for when the tech comes back out.

Also, dropping issues occur within an hour or so even after unplugging/power cycling and/or rebooting modem and router.

Thanks in advance.

AzzySpazbourne

Aspirant

Jan 10, 2023

Good afternoon,

Update: I decided to test at the site where the internet enters the home. Had modem plugged in now for about an hour, and so far, no uncorrectable errors on the downstream boned channels (so.. I guess that's a good sign? but it's only been an hour thus far...). Power still seems to be highly variant across the 32 channels ranging from a low of 7.7 to a high of 19.1. SNR, again, seems to have less, but still some borderline worrisome variance with a range of a low at 35.8 and a high of 38.7. Only thing I see on the upstream bonded channels is that the power for the 4th channel is not quite getting up to the desired minimum of 35.0. Now... for the Downstream OFDM channel, I'm getting a LOT of uncorrectable codewords that keep climbing and climbing and climbing by the minute. As of now though, no critical errors in the event log.. just recurring "notices" every few mins (CM-STATUS message sent. Event Type Code: 16 and 24).

My worry is now with no evidence of uncorrectable errors on the bonded downstream channels, that the ISP will again attempt to tell me it's a hardware issue on my end. Based on what I'm reading, the variance in power and SNR, and lack of getting consistent upstream power on all channels, there still looks to be an issue on the ISP side, no? I don't even have a clue about why the downstream OFCM is coughing up that many uncorrectables though? ISP is supposed to come tomorrow, and just want to make sure I'm armed with best info to finally get the issue resolved without further issues of recurrence.

Thanks to anybody who can give me pointers. Current Connection stats below (based on plugging modem in at site ISP cable enters home (i.e. bypassing ALL wiring in home). Also.. stats are based on just CAT 6A STP cable from modem to laptop without any other connections).

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Cable Connection

Cancel Apply

Frequency start Value

This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.

Starting Frequency

Startup Procedure

Procedure	Status	Comment
Acquire Downstream Channel	651000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Security	Disabled	Disabled

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	32	651000000 Hz	11.5 dBmV	36.4 dB	0	0
2	Locked	QAM256	1	465000000 Hz	10.8 dBmV	37.6 dB	0	0
3	Locked	QAM256	2	471000000 Hz	10.2 dBmV	37.4 dB	0	0
4	Locked	QAM256	4	483000000 Hz	11.8 dBmV	37.6 dB	0	0
5	Locked	QAM256	5	489000000 Hz	14.2 dBmV	38.3 dB	0	0
6	Locked	QAM256	8	507000000 Hz	16.4 dBmV	38.5 dB	0	0
7	Locked	QAM256	13	537000000 Hz	14.3 dBmV	38.5 dB	0	0
8	Locked	QAM256	14	543000000 Hz	15.6 dBmV	38.7 dB	0	0
9	Locked	QAM256	15	549000000 Hz	16.0 dBmV	38.6 dB	0	0
10	Locked	QAM256	17	561000000 Hz	14.5 dBmV	37.8 dB	0	0
11	Locked	QAM256	18	567000000 Hz	12.4 dBmV	37.2 dB	0	0
12	Locked	QAM256	19	573000000 Hz	10.9 dBmV	37.2 dB	0	0
13	Locked	QAM256	21	585000000 Hz	10.0 dBmV	37.8 dB	0	0
14	Locked	QAM256	22	591000000 Hz	9.9 dBmV	37.7 dB	0	0
15	Locked	QAM256	23	597000000 Hz	10.4 dBmV	37.2 dB	0	0
16	Locked	QAM256	24	603000000 Hz	11.6 dBmV	37.2 dB	0	0
17	Locked	QAM256	26	615000000 Hz	15.4 dBmV	37.4 dB	0	0
18	Locked	QAM256	27	621000000 Hz	15.9 dBmV	37.5 dB	0	0
19	Locked	QAM256	28	627000000 Hz	15.5 dBmV	37.7 dB	0	0
20	Locked	QAM256	29	633000000 Hz	14.6 dBmV	37.7 dB	0	0
21	Locked	QAM256	30	639000000 Hz	13.5 dBmV	37.4 dB	0	0
22	Locked	QAM256	34	663000000 Hz	12.2 dBmV	36.8 dB	0	0
23	Locked	QAM256	35	669000000 Hz	13.1 dBmV	37.0 dB	0	0
24	Locked	QAM256	36	675000000 Hz	14.1 dBmV	37.3 dB	0	0
25	Locked	QAM256	37	681000000 Hz	13.4 dBmV	37.5 dB	0	0
26	Locked	QAM256	38	687000000 Hz	11.2 dBmV	37.0 dB	0	0
27	Locked	QAM256	40	699000000 Hz	8.2 dBmV	35.9 dB	0	0
28	Locked	QAM256	41	705000000 Hz	7.7 dBmV	35.8 dB	0	0
29	Locked	QAM256	42	711000000 Hz	9.5 dBmV	36.0 dB	0	0
30	Locked	QAM256	43	717000000 Hz	12.7 dBmV	37.2 dB	0	0
31	Locked	QAM256	44	723000000 Hz	15.3 dBmV	37.7 dB	0	0
32	Locked	QAM256	47	741000000 Hz	19.1 dBmV	37.2 dB	0	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	1	5120	16600000 Hz	35.0 dBmV
2	Locked	ATDMA	2	5120	23000000 Hz	35.0 dBmV
3	Locked	ATDMA	3	5120	29400000 Hz	35.0 dBmV
4	Locked	ATDMA	4	5120	35800000 Hz	33.8 dBmV
5	Not Locked	Unknown	0	0	0 Hz	0.0 dBmV
6	Not Locked	Unknown	0	0	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0	0 Hz	0.0 dBmV

Downstream OFDM Channels

Channel	Lock Status	Profile ID	Channel ID	Frequency	Power	SNR / MER	Active Subcarrier Number Range	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Locked	0 ,1 ,2 ,3	49	212000000 Hz	12.2 dBmV	36.1 dB	1088 ~ 3007	68802730	51443103	4429109
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

Current System Time:Tue Jan 10 13:10:02 2023

System Up Time:01:20:44

FURRYe38
Guru - Experienced User
Jan 10, 2023
Power levels are way too high:

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

Any and all Errors and Criticals seen in the Event logs, the ISP needs to review and resolve.

Be sure your using a good quality LAN cable between the modem and router. CAT6A STP 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-Modems/m-p/1530376#M12853
- AzzySpazbourne
  Aspirant
  Jan 11, 2023
  Update:
  ISP tech came out today. He ran tests and said everything appeared to be "good" but I showed him all the screenshots of the communication stats with power level issues and varience issues, etc. Also showed him a live status of the stats that continued to happen.
  
  Again, he was at a loss and couldn't ID what the issue may be and suggested it might be a TAP issue. He didnt know why the power levels were that way, and didnt understand why I am getting so many uncorrectable codewords on the OFCM downstream channel.
  
  He also didnt know why my modem's security status was "disabled" and thought that was strange.
  
  He left saying he'll call the maintenence crew people to see if they can take a look, but he also said no one else in the neighborhood seems to be having this issue.
  
  Just to rule out everything, since this modem is compatible with Xfinity internet and voice plans.. could that be a reason why I'm having issues? The issues were occuring with the current ISP's (not comcast) modem I was renting, so thats why we tried this one... I'm not convinced though that maybe this modem might be creating a similar issue, but for a different reason or something? Anyone else have luck using this model with a non-Xfinity ISP? I do NOT want to drop another couple hundred bucks on a 2rd modem if I don't have to. .
  
  TIA
  - Kitsap
    Master
    Jan 11, 2023
    I am using a 2050V on Comcast. The reason the ISP tech organization is divided between home support and maintenance is it gives a built in path to pass the buck.
    
    Comcast is doing a great deal of system maintenance/upgrade in my area, Seattle WA, and my modem logs are often full. Also the signal power levels vary significantly from day to day. It does not seem to adversely affect performance. My DHCP leases on my router go through a cycle from 30 to 60 to 90 minutes then start over again.