JeffMcG's profile

Frequent Visitor

 • 

22 Messages

Friday, November 8th, 2024 10:45 PM

Frequent Internet Disconnects

We have been having frequent (1+ times a day) Internet disconnects for some time now. Thinking that it might be the modem, I installed a new modem the other day. But, the problem persists. From what I've seen in the logs, it is always a problem with the upstream (T3) connection dropping. At the end of this message I've attached  a screenshot of the modem log.

For testing purposes, I moved the modem as close to the point where the cable comes into the house as possible. There is one splitter in between the cable coming in from the street and the modem with only 6ft of cable between the splitter and the modem. The splitter was provided by Comcast.

Hopefully, the log provides some hint as to why we're experiencing these frequent disconnects.

Any help would be greatly appreciated.

Thank you,

-Jeff

Time

Priority

Description

1970-1-1, 00:01:11

Notice (6)

Honoring MDD; IP provisioning mode = IPv6

1970-1-1, 00:00:59

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:59

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:58

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:55

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:40

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

1970-1-1, 00:00:40

Notice (6)

WiFi Interface [wl1] set to Channel 153 (Side-Band Channel:N/A) - Reason:INIT

1970-1-1, 00:00:40

Notice (6)

WiFi Interface [wl0] set to Channel 11 (Side-Band Channel:N/A) - Reason:INIT

1970-1-1, 00:00:37

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:21:05

Critical (3)

No UCDs Received - Timeout;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:20:48

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:20:47

Critical (3)

No UCDs Received - Timeout;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:20:30

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:20:29

Critical (3)

No UCDs Received - Timeout;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:20:12

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:20:11

Critical (3)

No UCDs Received - Timeout;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:19:54

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:19:53

Critical (3)

No UCDs Received - Timeout;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:19:36

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:19:35

Critical (3)

No UCDs Received - Timeout;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:19:16

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=00:90:f0:0c:04:00;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:13:41

Critical (3)

No Ranging Response received - T3 time-out;CM-MAC=**********;CMTS-MAC=00:90:f0:0c:04:00;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:13:27

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=00:90:f0:0c:04:00;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:09:34

Critical (3)

No Ranging Response received - T3 time-out;CM-MAC=**********;CMTS-MAC=00:90:f0:0c:04:00;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:29

Critical (3)

No Ranging Response received - T3 time-out;CM-MAC=**********;CMTS-MAC=00:90:f0:0c:04:00;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:22

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:20

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:17

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:16

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:08

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:07

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:07

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:06

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:04

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:02

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:05:02

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:04:59

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:04:58

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:04:49

Critical (3)

SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

2024-11-8, 20:04:48

Critical (3)

No UCDs Received - Timeout;;CM-MAC=**********;CMTS-MAC=**********;CM-QOS=1.0;CM-VER=3.0;

Expert

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107.1K Messages

15 days ago

@JeffMcG 

Your post with that pic of the error log entries was marked as being "Private" by the forum bot because it contains CM MAC and the CMTS MAC addresses. They are considered to be personal information. The posting of personally identifiable information is a violation of their forum guidelines. Please delete that pic only.

What you can do instead is to copy all of the text (instead of using an image) and paste it into your next post here, but you'll need to redact all of the CM MAC and CMTS MAC addresses. The bot will not allow your post to be seen publicly.

Frequent Visitor

 • 

22 Messages

As you suggested. I have removed the previous image and replaced with redacted text.

Official Employee

 • 

1.6K Messages

 

JeffMcG Thank you so much for reaching out for help with your connection issues.  We appreciate you providing the redacted details for us to check out. Could I ask what modem you are using and the speed you currently have? Have you also checked out the full RF signals? You can heck out our troubleshooting Tips page to see the ranges we work in if you check out the Check your Signal Levels section. 

 

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

Frequent Visitor

 • 

22 Messages

Hello Amanda,

Sorry for the delay in responding. I only received the email notification that you had replied to my post yesterday.

In response to your questions:

  • The modem is a Netgear C7000v2. It's brand new; right out of the box.
  • I tried to access our expected U/D speeds but there seems to be a problem with the Xfinity website today.  I'll keep trying. But, I think our plan calls for 250-300mbps down and maybe 50mbps up.
  • In reality, we get around 20mbps down and 15mbps up. That's over wireless.
  • Here is the channel information you requested. I can see that only 4 of the 8 upstream channels are locked and those that are locked have power levels of 50+dBmV

    Startup Procedure

    Procedure

    Status

    Comment

    Acquire Downstream Channel

    417000000 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

    4

    417000000 Hz

    4.3 dBmV

    40.2 dB

    0

    0

    2

    Locked

    QAM256

    1

    399000000 Hz

    4.2 dBmV

    39.6 dB

    0

    0

    3

    Locked

    QAM256

    2

    405000000 Hz

    3.1 dBmV

    39.9 dB

    0

    0

    4

    Locked

    QAM256

    3

    411000000 Hz

    3.2 dBmV

    39.7 dB

    0

    0

    5

    Locked

    QAM256

    5

    423000000 Hz

    4.7 dBmV

    40.3 dB

    0

    0

    6

    Locked

    QAM256

    6

    429000000 Hz

    4.9 dBmV

    40.3 dB

    0

    0

    7

    Locked

    QAM256

    7

    435000000 Hz

    5 dBmV

    40.2 dB

    0

    0

    8

    Locked

    QAM256

    8

    441000000 Hz

    5 dBmV

    40.2 dB

    0

    0

    9

    Locked

    QAM256

    9

    447000000 Hz

    5 dBmV

    40.2 dB

    0

    0

    10

    Locked

    QAM256

    10

    453000000 Hz

    5.2 dBmV

    40.5 dB

    0

    0

    11

    Locked

    QAM256

    11

    459000000 Hz

    5.1 dBmV

    40.8 dB

    0

    0

    12

    Locked

    QAM256

    12

    465000000 Hz

    5.2 dBmV

    41.3 dB

    0

    0

    13

    Locked

    QAM256

    13

    471000000 Hz

    5.4 dBmV

    41.9 dB

    0

    0

    14

    Locked

    QAM256

    14

    477000000 Hz

    5.4 dBmV

    41.9 dB

    0

    0

    15

    Locked

    QAM256

    15

    483000000 Hz

    5.4 dBmV

    41.9 dB

    0

    0

    16

    Locked

    QAM256

    16

    489000000 Hz

    5.5 dBmV

    42.2 dB

    0

    0

    17

    Locked

    QAM256

    17

    495000000 Hz

    4.7 dBmV

    41.4 dB

    0

    0

    18

    Locked

    QAM256

    18

    501000000 Hz

    4.4 dBmV

    40.8 dB

    0

    0

    19

    Locked

    QAM256

    19

    507000000 Hz

    4.5 dBmV

    40.9 dB

    0

    0

    20

    Locked

    QAM256

    20

    513000000 Hz

    4.5 dBmV

    40.8 dB

    0

    0

    21

    Locked

    QAM256

    21

    519000000 Hz

    4.3 dBmV

    40.5 dB

    0

    0

    22

    Locked

    QAM256

    22

    525000000 Hz

    4.4 dBmV

    40.8 dB

    0

    0

    23

    Locked

    QAM256

    23

    531000000 Hz

    4.4 dBmV

    40.8 dB

    0

    0

    24

    Locked

    QAM256

    24

    537000000 Hz

    4.3 dBmV

    40.8 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

    16400000 Hz

    53.5 dBmV

    2

    Locked

    ATDMA

    2

    5120 Ksym/sec

    22800000 Hz

    51.9 dBmV

    3

    Locked

    ATDMA

    3

    5120 Ksym/sec

    29200000 Hz

    52 dBmV

    4

    Locked

    ATDMA

    4

    5120 Ksym/sec

    35600000 Hz

    51.7 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

Hopefully this information is helpful to you.

Thank you,

-Jeff

Official Employee

 • 

1.7K Messages

Greetings again, @JeffMcG! I just wanted to touch base and see if you were able to go through the suggestions offered by @EG, or if we needed to get a technician out there to check things out. Please let me know if there's any way we can be of assistance.

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

Expert

 • 

107.1K Messages

7 days ago

@JeffMcG 

The upstream power is too high / out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, etc.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.


Good luck with it !

Frequent Visitor

 • 

22 Messages

I have plugged the cable from the street directly into the back of the modem (no splitters involved at all). But, I'm still seeing upstream power levels in 50dBmV range. And, only 4 of the 8 channels lock. Am I correct in concluding that this is almost certainly a problem with the line coming in from the street?

Thank you,

-Jeff

Official Employee

 • 

1.7K Messages

It definitely could be a possibility, @JeffMcG. Thank you for looking into that and getting back to us. It sounds like we may need to get someone out there to see if those signals can be corrected.

 

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.

 

To send a Direct Message, please click on the “Direct Message” icon in the top-right corner of the screen, next to the bell icon, click the "New message" (pencil and paper) icon, then type or select "Xfinity Support". Type your message in the text area near the bottom of the window and press Enter to send your message and initiate a live session.

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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