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T3 and T4 Time Outs, High Downstream Power Levels, SYNC Timing Synchronization Failures, and more!

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T3 and T4 Time Outs, High Downstream Power Levels, SYNC Timing Synchronization Failures, and more!

For the past few weeks or so I have been experiencing significant ping spikes and high latency variations with very high loaded latency, drops in speed >400mbps, intermittent disconnects, severe packet loss, and trouble connecting to servers for downloads (Adobe CC won't even download as it cannot call back to Adobe servers.) I have tried to adjust firewall settings on my computer, create inbound port rules, manually assign DNS, and a few others I honestly can't remember at this moment. And forget about online gaming. If I ever even can connect to a game server, ping spikes and severe lag end up kicking me out of game.

 

I am using an Arris SB8200 modem with new coax cables provided by Comcast upon installation about 8 months ago. The modem is direct to the line with nothing upstream other than the connection coming into the house. Modem logs:

 

 

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 573000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK  
Security Enabled BPI+
DOCSIS Network Access Enabled Allowed  

 
Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
21 Locked QAM256 573000000 Hz 8.5 dBmV 42.6 dB 0 0
9 Locked QAM256 501000000 Hz 8.0 dBmV 42.7 dB 0 0
10 Locked QAM256 507000000 Hz 8.2 dBmV 42.6 dB 0 0
11 Locked QAM256 513000000 Hz 8.2 dBmV 42.5 dB 0 0
12 Locked QAM256 519000000 Hz 8.1 dBmV 42.5 dB 0 0
13 Locked QAM256 525000000 Hz 8.1 dBmV 42.6 dB 0 0
14 Locked QAM256 531000000 Hz 8.1 dBmV 42.5 dB 0 0
15 Locked QAM256 537000000 Hz 8.1 dBmV 42.5 dB 0 0
16 Locked QAM256 543000000 Hz 8.2 dBmV 42.6 dB 0 0
17 Locked QAM256 549000000 Hz 8.2 dBmV 42.6 dB 0 0
18 Locked QAM256 555000000 Hz 8.0 dBmV 42.5 dB 0 0
19 Locked QAM256 561000000 Hz 8.0 dBmV 42.4 dB 0 0
20 Locked QAM256 567000000 Hz 8.1 dBmV 42.5 dB 0 0
22 Locked QAM256 579000000 Hz 8.6 dBmV 42.6 dB 0 0
23 Locked QAM256 585000000 Hz 8.8 dBmV 42.6 dB 0 0
24 Locked QAM256 591000000 Hz 8.7 dBmV 42.6 dB 0 0
25 Locked QAM256 597000000 Hz 9.0 dBmV 42.7 dB 0 0
26 Locked QAM256 603000000 Hz 9.0 dBmV 42.7 dB 0 0
27 Locked QAM256 609000000 Hz 8.8 dBmV 42.7 dB 0 0
28 Locked QAM256 615000000 Hz 8.7 dBmV 42.6 dB 0 0
29 Locked QAM256 621000000 Hz 8.9 dBmV 42.7 dB 0 0
30 Locked QAM256 627000000 Hz 9.1 dBmV 42.7 dB 0 0
31 Locked QAM256 633000000 Hz 8.9 dBmV 42.7 dB 0 0
32 Locked QAM256 639000000 Hz 8.9 dBmV 42.6 dB 0 0
33 Locked QAM256 645000000 Hz 9.0 dBmV 42.7 dB 0 0
34 Locked QAM256 651000000 Hz 9.1 dBmV 42.8 dB 0 0
35 Locked QAM256 657000000 Hz 9.2 dBmV 42.8 dB 0 0
36 Locked QAM256 663000000 Hz 9.2 dBmV 42.6 dB 0 0
37 Locked QAM256 669000000 Hz 9.2 dBmV 42.8 dB 0 0
38 Locked QAM256 675000000 Hz 9.4 dBmV 41.8 dB 0 0
39 Locked QAM256 681000000 Hz 9.8 dBmV 43.0 dB 0 0
40 Locked QAM256 687000000 Hz 10.2 dBmV 43.1 dB 0 0
159 Locked Other 722000000 Hz 11.9 dBmV 41.8 dB 65800440 0



 
Upstream Bonded Channels
Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 5 Locked SC-QAM Upstream 36100000 Hz 6400000 Hz 44.0 dBmV
2 6 Locked SC-QAM Upstream 29600000 Hz 6400000 Hz 45.0 dBmV
3 7 Locked SC-QAM Upstream 23000000 Hz 6400000 Hz 44.0 dBmV
4 8 Locked SC-QAM Upstream 16500000 Hz 6400000 Hz 43.0 dBmV



 

Current System Time: Tue Apr 14 13:44:01 2020

 

Modem Events Log:

 

Date Time Event ID Event Level Description
04/14/2020 13:43 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 2436694066 6 "Honoring MDD; IP provisioning mode = IPv6"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
04/14/2020 13:30 2436694044 3 "Resetting the cable modem due to docsDevResetNow"
04/14/2020 09:43 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
04/13/2020 08:59 2436694044 3 "Resetting the cable modem due to docsDevResetNow"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
04/12/2020 14:17 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/15/2020 11:30 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:01 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:56 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:07 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:05 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:03 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:03 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:45 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:45 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:45 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:45 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:44 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:44 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:44 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:44 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:43 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
03/12/2020 00:43 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
02/28/2020 15:00 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
02/28/2020 15:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
02/28/2020 15:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
02/28/2020 15:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=0c:11:67:03:2b:1f;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=8c:61:a3:cb:a8:85;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"

 

I have tried factory resets on modem and router, replacing cables and checking connections, disabling IPv6, cmd actions such as release and renew, flush dns and arp cache. Cmd ping and pathping will usually return a timeout when pinging google.com, as will tracert.

 

Neighbors are also experiencing issues. I believe all of these problems are most likely due to line issues outside of our house. You can see errors in the event log from before the past few weeks, but everything has been significantly worse the past 10 days or so...conveniently after several storms.

 

Please please please help me out if you can. I understand the current state of tech support with Xfinity is almost none due to limited resources amid COVID-19 precautions, but getting a tech out to check physical connections and line issues outside of the home would be great.

 

Thank you in advance.

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New Poster

Re: T3 and T4 Time Outs, High Downstream Power Levels, SYNC Timing Synchronization Failures, and mor

@EG Would you be able to help? Support is telling me it's an equipment issue, which makes no sense to me.

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Regular Visitor

Re: T3 and T4 Time Outs, High Downstream Power Levels, SYNC Timing Synchronization Failures, and mor

I am curious on how your upstream is so high. Are both your modem downstream/upstream lights blue?

I am having a huge fight with comcast about this.

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Official Employee

Re: T3 and T4 Time Outs, High Downstream Power Levels, SYNC Timing Synchronization Failures, and mor

Hello Sturdy. Thank you for creating a post on our Forum. Apologies for our delay in getting to your post. I can assist with further troubleshooting if needed. To get started, please send me a private message and include your full name so I can access your equipment. 


I am an Official Comcast Employee.
Official Employees are from multiple teams within Comcast: CARE, Product, Leadership. We ask that you post publicly so people with similar questions may benefit from the conversation.
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