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user_947dbf
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Thursday, February 20th, 2025 8:39 PM

Dropped internet connection with Modem log

I have an unstable connection, and here is the log my modem is kicking out constantly (MAC addresses censored by me):

hu Feb 20 15:07:36 2025 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=********;CMTS-MAC=**********;CM-QOS=1.1;CM-VER=3.1;
Thu Feb 20 15:05:34 2025 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.1;CM-VER=3.1;
Thu Feb 20 15:05:34 2025 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=**********;CMTS-MAC=0**********;CM-QOS=1.1;CM-VER=3.1;
Thu Feb 20 15:02:36 2025 Notice (6) CM-STATUS message sent. Event Type Code: 16; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.1;CM-VER=3.1;
Thu Feb 20 15:02:32 2025 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.1;CM-VER=3.1;
Thu Feb 20 15:02:11 2025 Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.1;CM-VER=3.1;

It's just a variation of this over and over. What needs to be done to fix this?

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2 months ago

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EG

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109.7K Messages

2 months ago

Please also copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.


What is the exact make and model number of the modem / gateway device ?

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user_947dbf

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I believe this is what you are looking for? Netgear CM1200

Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 20 565750000 Hz 10.3 dBmV 45.2 dB 0 0
2 Locked QAM256 13 523750000 Hz 10.3 dBmV 45.4 dB 0 0
3 Locked QAM256 14 529750000 Hz 10.3 dBmV 45.4 dB 0 0
4 Locked QAM256 15 535750000 Hz 10.5 dBmV 45.3 dB 0 0
5 Locked QAM256 16 541750000 Hz 10.2 dBmV 44.9 dB 0 0
6 Locked QAM256 17 547750000 Hz 10.4 dBmV 44.7 dB 0 0
7 Locked QAM256 18 553750000 Hz 10.1 dBmV 44.7 dB 0 0
8 Locked QAM256 19 559750000 Hz 10.4 dBmV 45.3 dB 0 0
9 Locked QAM256 21 571750000 Hz 10.4 dBmV 45.2 dB 0 0
10 Locked QAM256 22 577750000 Hz 10.5 dBmV 45.2 dB 0 0
11 Locked QAM256 23 583750000 Hz 10.4 dBmV 45.2 dB 0 0
12 Locked QAM256 24 589750000 Hz 10.6 dBmV 45.2 dB 0 0
13 Locked QAM256 25 595750000 Hz 10.5 dBmV 45.2 dB 0 0
14 Locked QAM256 26 601750000 Hz 10.7 dBmV 45.2 dB 0 0
15 Locked QAM256 27 607750000 Hz 10.5 dBmV 45.1 dB 0 0
16 Locked QAM256 28 613750000 Hz 10.6 dBmV 45.1 dB 0 0
17 Locked QAM256 29 619750000 Hz 10.7 dBmV 45 dB 0 0
18 Locked QAM256 30 625750000 Hz 10.8 dBmV 44.1 dB 0 0
19 Locked QAM256 31 631750000 Hz 11 dBmV 44.4 dB 0 0
20 Locked QAM256 32 637750000 Hz 11 dBmV 44.6 dB 0 0
21 Locked QAM256 33 643750000 Hz 11.4 dBmV 45.2 dB 0 0
22 Locked QAM256 34 649750000 Hz 11.3 dBmV 45.2 dB 0 0
23 Locked QAM256 35 655750000 Hz 11.5 dBmV 45.3 dB 0 0
24 Locked QAM256 36 661750000 Hz 11.4 dBmV 45.2 dB 0 0
25 Locked QAM256 37 667750000 Hz 11.5 dBmV 45.2 dB 0 0
26 Locked QAM256 38 673750000 Hz 11.5 dBmV 44.2 dB 0 0
27 Locked QAM256 39 679750000 Hz 11.2 dBmV 45.1 dB 0 0
28 Locked QAM256 40 685750000 Hz 11.3 dBmV 45.1 dB 0 0
29 Locked QAM256 41 691750000 Hz 10.9 dBmV 44.9 dB 0 0
30 Locked QAM256 42 697750000 Hz 11 dBmV 44.9 dB 0 0
31 Locked QAM256 43 703750000 Hz 10.8 dBmV 44.8 dB 0 0
32 Locked QAM256 44 709750000 Hz 10.9 dBmV 44.9 dB 0 0

Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 17 5120 Ksym/sec 16400000 Hz 45.8 dBmV
2 Locked ATDMA 18 5120 Ksym/sec 22800000 Hz 45.8 dBmV
3 Locked ATDMA 19 5120 Ksym/sec 29200000 Hz 45.5 dBmV
4 Locked ATDMA 20 5120 Ksym/sec 35600000 Hz 45.8 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 ,3 193 957000000 Hz 12.5 dBmV 44.2 dB 148 ~ 3947 156193216 109203672 332254
2 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0

(edited)

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2 months ago

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XfinityOrlandoM

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2 months ago

@user_947dbf

 

Thanks for reaching out to us we do apologize for any inconvenience you're having with your Internet connection. This link https://www.xfinity.com/support/articles/internet-connectivity-troubleshooting has great information on how you can troubleshoot your Internet connection through our awesome Xfinity app.

 

 Our awesome chat assistant will go through some steps to remotely try and fix the connection issues with you,  if the issues are not able to be fixed remotely our awesome chat assistant will connect you with a live agent that can schedule for a technician to come out.

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EG

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109.7K Messages

2 months ago

@user_947dbf 

Did you have a chance to gather the info that I requested ? Please respond right here in your topic on these public help forums. Thank you.

(edited)

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user_947dbf

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The problem seems to occur at certain points in the day: Mainly starting at or just before 12:00PM EST, and then gets better at around 3:30 EST, then degrades at some point in the evening (haven't pinpointed that time yet). It is currently 10:15AM and it seems to be working perfectly fine. I know it sounds crazy that the internet connection seems to degrade at certain times of the day, but that's what I am experiencing. The above information was taken last night when it was not working, and here is the same information right now taken as it is working:

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 565750000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD IPv6 only
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 20 565750000 Hz 9.2 dBmV 45.1 dB 0 0
2 Locked QAM256 1 451750000 Hz 8.1 dBmV 45 dB 0 0
3 Locked QAM256 2 457750000 Hz 7.8 dBmV 44.8 dB 0 0
4 Locked QAM256 3 463750000 Hz 7.9 dBmV 44.9 dB 0 0
5 Locked QAM256 4 469750000 Hz 8 dBmV 44.9 dB 0 0
6 Locked QAM256 5 475750000 Hz 8.3 dBmV 45 dB 0 0
7 Locked QAM256 6 481750000 Hz 8.5 dBmV 45.1 dB 0 0
8 Locked QAM256 7 487750000 Hz 8.5 dBmV 45.1 dB 0 0
9 Locked QAM256 8 493750000 Hz 8.9 dBmV 45.3 dB 0 0
10 Locked QAM256 9 499750000 Hz 8.7 dBmV 45.2 dB 0 0
11 Locked QAM256 10 505750000 Hz 9.1 dBmV 45.3 dB 0 0
12 Locked QAM256 11 511750000 Hz 8.9 dBmV 45.2 dB 0 0
13 Locked QAM256 12 517750000 Hz 9.2 dBmV 45.3 dB 0 0
14 Locked QAM256 13 523750000 Hz 9.2 dBmV 45.4 dB 0 0
15 Locked QAM256 14 529750000 Hz 9.2 dBmV 45.4 dB 0 0
16 Locked QAM256 15 535750000 Hz 9.4 dBmV 45.3 dB 0 0
17 Locked QAM256 16 541750000 Hz 9 dBmV 45 dB 0 0
18 Locked QAM256 17 547750000 Hz 9.3 dBmV 45 dB 0 0
19 Locked QAM256 18 553750000 Hz 9 dBmV 44.8 dB 0 0
20 Locked QAM256 19 559750000 Hz 9.3 dBmV 45.2 dB 0 0
21 Locked QAM256 21 571750000 Hz 9.2 dBmV 45.1 dB 0 0
22 Locked QAM256 22 577750000 Hz 9.3 dBmV 45.2 dB 0 0
23 Locked QAM256 23 583750000 Hz 9.2 dBmV 45.1 dB 0 0
24 Locked QAM256 24 589750000 Hz 9.4 dBmV 45.2 dB 0 0
25 Locked QAM256 25 595750000 Hz 9.4 dBmV 45.1 dB 0 0
26 Locked QAM256 26 601750000 Hz 9.6 dBmV 45.1 dB 0 0
27 Locked QAM256 27 607750000 Hz 9.4 dBmV 45.1 dB 0 0
28 Locked QAM256 28 613750000 Hz 9.4 dBmV 45 dB 0 0
29 Locked QAM256 29 619750000 Hz 9.6 dBmV 44.9 dB 0 0
30 Locked QAM256 30 625750000 Hz 9.6 dBmV 44.8 dB 0 0
31 Locked QAM256 31 631750000 Hz 9.9 dBmV 44.7 dB 0 0
32 Locked QAM256 32 637750000 Hz 9.9 dBmV 44.8 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 17 5120 Ksym/sec 16400000 Hz 45.5 dBmV
2 Locked ATDMA 18 5120 Ksym/sec 22800000 Hz 45.5 dBmV
3 Locked ATDMA 19 5120 Ksym/sec 29200000 Hz 45.5 dBmV
4 Locked ATDMA 20 5120 Ksym/sec 35600000 Hz 45.5 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 ,3 193 957000000 Hz 11.4 dBmV 44.2 dB 148 ~ 3947 92904992 65417192 13238
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

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2 months ago

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EG

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109.7K Messages

2 months ago

@user_947dbf 

This may or may not be the root cause of the problem (YMMV) but it should be addressed regardless.


The downstream power is too high / out of spec. It may be over-driving the front-end receiver circuit of the modem. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.


Is there a drop amplifier on the coax cable line leading to the modem ? If so, try removing / bypassing it and see. If not, you can try installing a -6 dB forward path-only attenuator pad such as this one on the coax port on the rear of the modem to knock that power level down and see;

https://www.amazon.com/line-Signal-Forward-Attenuator-FPA6-54/dp/B07882H96R

For areas that have been upgraded to the new Next Gen (mid-split) upload speeds;

https://www.multicominc.com/product/multicom-mul-fpa85-forward-path-attenuator  

These won't affect the upload power which is within specs.

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user_947dbf

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Would these be items a technician would have? Don't really want to have to order this for it not to work. I don't see a drop amplifier.

Additionally, it is now 1130AM and the connection is noticeably degraded. Not unusable yet, but getting there. Why is it the same time every day? What happens to the connection?

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2 months ago

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user_947dbf

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@EG​ It is 2:30pm and the internet is stable. I made ZERO changes. What is going on here? (Not saying you will know, just asking in general, as it is just so odd.)

Posting latest from the modem Power levels seem lower....is that it? What controls the power levels?

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 565750000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD IPv6 only
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 20 565750000 Hz 8.4 dBmV 44.9 dB 0 0
2 Locked QAM256 1 451750000 Hz 7.9 dBmV 45.2 dB 0 0
3 Locked QAM256 2 457750000 Hz 7.7 dBmV 45.3 dB 0 0
4 Locked QAM256 3 463750000 Hz 8 dBmV 45.2 dB 0 0
5 Locked QAM256 4 469750000 Hz 7.9 dBmV 45.2 dB 0 0
6 Locked QAM256 5 475750000 Hz 8 dBmV 45.2 dB 0 0
7 Locked QAM256 6 481750000 Hz 8.2 dBmV 45.3 dB 0 0
8 Locked QAM256 7 487750000 Hz 8.1 dBmV 45.2 dB 0 0
9 Locked QAM256 8 493750000 Hz 8.5 dBmV 45.4 dB 0 0
10 Locked QAM256 9 499750000 Hz 8.2 dBmV 45.2 dB 0 0
11 Locked QAM256 10 505750000 Hz 8.5 dBmV 45.2 dB 0 0
12 Locked QAM256 11 511750000 Hz 8.3 dBmV 45.2 dB 0 0
13 Locked QAM256 12 517750000 Hz 8.5 dBmV 45.3 dB 0 0
14 Locked QAM256 13 523750000 Hz 8.6 dBmV 45.3 dB 0 0
15 Locked QAM256 14 529750000 Hz 8.4 dBmV 45.2 dB 0 0
16 Locked QAM256 15 535750000 Hz 8.3 dBmV 45 dB 0 0
17 Locked QAM256 16 541750000 Hz 7.8 dBmV 44.7 dB 0 0
18 Locked QAM256 17 547750000 Hz 8 dBmV 44.5 dB 0 0
19 Locked QAM256 18 553750000 Hz 7.9 dBmV 44.7 dB 0 0
20 Locked QAM256 19 559750000 Hz 8.4 dBmV 45 dB 0 0
21 Locked QAM256 21 571750000 Hz 8.5 dBmV 45 dB 0 0
22 Locked QAM256 22 577750000 Hz 8.6 dBmV 45 dB 0 0
23 Locked QAM256 23 583750000 Hz 8.5 dBmV 45.1 dB 0 0
24 Locked QAM256 24 589750000 Hz 8.8 dBmV 45.1 dB 0 0
25 Locked QAM256 25 595750000 Hz 8.7 dBmV 45.1 dB 0 0
26 Locked QAM256 26 601750000 Hz 8.9 dBmV 45 dB 0 0
27 Locked QAM256 27 607750000 Hz 8.7 dBmV 45 dB 0 0
28 Locked QAM256 28 613750000 Hz 8.7 dBmV 44.9 dB 0 0
29 Locked QAM256 29 619750000 Hz 8.9 dBmV 44.9 dB 0 0
30 Locked QAM256 30 625750000 Hz 8.9 dBmV 44.4 dB 0 0
31 Locked QAM256 31 631750000 Hz 9.3 dBmV 44.3 dB 0 0
32 Locked QAM256 32 637750000 Hz 9.2 dBmV 44.3 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 17 5120 Ksym/sec 16400000 Hz 45.5 dBmV
2 Locked ATDMA 18 5120 Ksym/sec 22800000 Hz 45.5 dBmV
3 Locked ATDMA 19 5120 Ksym/sec 29200000 Hz 45.5 dBmV
4 Locked ATDMA 20 5120 Ksym/sec 35600000 Hz 45.5 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 ,3 193 957000000 Hz 10.7 dBmV 43.8 dB 148 ~ 3947 128181398 80118250 107129
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

(edited)

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2 months ago

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XfinityChelseaB

Official Employee

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1.6K Messages

@user_947dbf, If you could send our team a direct message with your full name, the name listed on the account (if different), and the service address associated with your account, I'd be more than happy to look into this for you and see about getting a technician out to you to look into your connection concern further. To send a Direct Message, please click on the chat icon in the top-right corner of the screen, next to the bell icon, and then type or select "Xfinity Support" to initiate a direct message

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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2 months ago

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