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user_c26111
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Tue, Aug 16, 2022 9:46 AM

Constant connection drops and "SYNC Timing Synchronization failure"/"No Ranging Response received - T3 time-out" errors

Background

I began having constant connection drop issues a few months ago which resulted in a service tech coming out  where they ultimately ended up removing a splitter where the line came into the house and replacing the cable end where the line connects to the house line.

This seemed to resolve the issue until a few weeks back when it started occurring again.

After tolerating the connection drops the last few weeks, I went ahead and replaced replaced the Xfinity modem with my own Motorola MB6811 and the symptoms have persisted through this change.

I decided to check out the event logs in the new modem and found that since I've been using the new modem, I have been getting "SYNC Timing Synchronization failure"/"No Ranging Response received - T3 time-out" errors numerous times a day corresponding to times when my internet connection would suddenly drop out.

I've provided the Connection Details page information as well as the relevant log entries with redacted MAC addresses below.

I've experienced these symptoms now on and off for the entire 3 years I've been at this house and similar issues 5 years ago while living in a house just 5 homes down the street. It's in an older neighborhood and I've long suspected that there is some aging equipment in our little area causing these issues.

Please let me know if there is anything else you need me to provide.

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

19:56:04 Sat Aug 13 2022 	 	Critical (3)	 	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

21:04:52 Sun Aug 14 2022 	 	Critical (3)	 	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

21:05:01 Sun Aug 14 2022 	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

21:05:03 Sun Aug 14 2022 	 	Critical (3)	 	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

21:05:03 Sun Aug 14 2022 	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

23:38:06 Sun Aug 14 2022 	 	Critical (3)	 	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

23:38:15 Sun Aug 14 2022 	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

09:37:38 Mon Aug 15 2022 	 	Critical (3)	 	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;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=xx:xx:xx:xx:xx:xx:;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Critical (3)	 	No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

Time Not Established	 	Notice (6)	 	Honoring MDD; IP provisioning mode = IPv6

02:52:04 Tue Aug 16 2022 	 	Notice (6)	 	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

02:52:22 Tue Aug 16 2022 	 	Notice (6)	 	CM-STATUS message sent. Event Type Code: 24; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=xx:xx:xx:xx:xx:xx:;CMTS-MAC=xx:xx:xx:xx:xx:xx:;CM-QOS=1.1;CM-VER=3.1;

Connection
   Startup Sequence    
   Startup Step Status Comment

  
   Acquire Downstream Channel 525000000 Hz Locked
  
   Upstream Connection OK Operational
  
   Boot State OK Operational

  
   Configuration File OK
  
   Security Enabled BPI+
  


   Connection Status    
   System Up Time 0 days 00h:21m:43s  
  
   Network Access Allowed  
  


   Downstream Bonded Channels  
  
   Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected
   1 Locked QAM256 20 525.0 7.6 40.4 29 4
   2 Locked QAM256 4 411.0 7.9 41.3 48 33
   3 Locked QAM256 5 417.0 7.9 41.2 60 29
   4 Locked QAM256 6 435.0 7.8 41.0 17 32
   5 Locked QAM256 7 441.0 7.5 40.9 9 32
   6 Locked QAM256 8 453.0 7.4 40.9 9 30
   7 Locked QAM256 9 459.0 7.1 40.9 13 29
   8 Locked QAM256 10 465.0 6.8 40.8 18 29
   9 Locked QAM256 11 471.0 6.4 40.7 11 27
   10 Locked QAM256 12 477.0 6.3 40.5 19 26
   11 Locked QAM256 13 483.0 6.6 40.6 14 28
   12 Locked QAM256 14 489.0 7.1 40.7 11 31
   13 Locked QAM256 15 495.0 7.4 40.8 10 28
   14 Locked QAM256 16 501.0 7.6 40.8 10 29
   15 Locked QAM256 17 507.0 7.7 40.8 10 26
   16 Locked QAM256 18 513.0 7.7 40.7 7 28
   17 Locked QAM256 19 519.0 7.5 40.4 31 8
   18 Locked QAM256 21 531.0 7.6 40.4 7 28
   19 Locked QAM256 22 537.0 7.6 40.4 9 25
   20 Locked QAM256 23 543.0 7.6 40.2 6 27
   21 Locked QAM256 24 549.0 7.3 40.1 24 9
   22 Locked QAM256 25 555.0 7.4 40.2 10 23
   23 Locked QAM256 26 561.0 7.3 40.1 10 24
   24 Locked QAM256 27 567.0 7.3 40.0 7 27
   25 Locked QAM256 28 573.0 7.1 39.8 7 26
   26 Locked QAM256 29 579.0 7.0 39.7 6 29
   27 Locked QAM256 30 585.0 7.0 39.8 11 23
   28 Locked QAM256 31 591.0 7.2 39.7 10 23
   29 Locked QAM256 32 597.0 7.6 39.8 6 27
   30 Locked QAM256 33 603.0 7.8 39.8 7 26
   31 Locked QAM256 34 609.0 8.1 39.9 31 1
   32 Locked OFDM PLC 48 722.0 11.4 39.6 17075067 5


   Upstream Bonded Channels  
  
   Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)
   1 Locked SC-QAM 1 2560 10.4 44.5
   2 Locked SC-QAM 2 5120 16.4 43.8
   3 Locked SC-QAM 3 5120 22.8 43.0
   4 Locked SC-QAM 4 5120 29.2 42.3
   5 Locked SC-QAM 5 5120 35.6 41.5
   6 Locked SC-QAM 11 2560 40.4 42.5

Question

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Updated 

1 m ago

 • Edited

52

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XfinityJamesC

Official Employee

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648 Messages

1 m ago

Greetings, @user_c26111! I hope your week has been treating you well. Thanks so much for taking a moment out of your busy day to leave a post on our community forum. I'm sorry to hear you're having issues with your service, but you have definitely come to the right place for assistance.

 

If you were having the exact same issue across multiple modems, then it stands to reason the issue is happening at some point before the signal reaches your modem. It seems like the connection points that were replaced by the technician made a difference at first, but if the issues returned after a period of time, then there may be more points of degradation along the line path that need to be checked out.

 

If you could send our team a private 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 Private 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 live session.

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user_c26111

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2 Messages

1 m ago

Just wanted to update the post with the most recent information.

A technician was sent out on Tuesday and, just like the previous visits, the technician replaced a couple of cable fittings and reset the modem which has not resolved the issue.

I wrote a custom script that grabs the modem logs every couple of minutes while my laptop is running and while the occurrences have gone down in frequency, they are still occurring daily.

Most recent logs

Time Not Established  Critical (3) SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Time Not Established  Critical (3) No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;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=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Time Not Established  Critical (3) No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;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=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Time Not Established  Critical (3) No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
18:55:16 Thu Aug 25 2022 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
10:05:36 Fri Aug 26 2022 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
10:05:36 Fri Aug 26 2022 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
10:05:36 Fri Aug 26 2022 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;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=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
Time Not Established  Critical (3) No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
Time Not Established  Notice (6) Honoring MDD; IP provisioning mode = IPv6
10:23:34 Fri Aug 26 2022 Notice (6) DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;
10:23:49 Fri Aug 26 2022 Notice (6) CM-STATUS message sent. Event Type Code: 24; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;%

Still communicating over DM with Comcast and will keep this post updated with any developments.

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