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Intermittent dropped connectivity - uncorrectables in downstream and low power in upstream

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Regular Visitor

Intermittent dropped connectivity - uncorrectables in downstream and low power in upstream

Hi All,

 

I've browsed this subject a lot over the past few days and saw a lot of support from members and xfinity support on advanced issues. So in leui of calling customer support one more time and being asked to reset my modem and router a 100 times, I'm hoping someone here may be able to help me diagnose the issue.

 

We just moved into a new house and we upgraded to a 300mbps connection (from 120mbps). As part of that, we got an SB8200 modem to be future proof. When we initially moved in, our speeds were around 30mbps and we were experiencing intermittent dropped connections. After having three techs out over a period of three weeks, the last tech finally replaced the drop and that fixed the speed issue. We thought this would also fix the intermittent connection drops but unfortunately it didn't. We don't have any splitters in the house, just one modem. The outside drop goes to a connector which is bonded, through the basement to another connector (not sure why this is there, then finally directly to the modem (no wall outlet). Here are the screenshots of the modem status and log:

 

Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
37 Locked QAM256 675000000 Hz 5.5 dBmV 38.6 dB 0 0
9 Locked QAM256 507000000 Hz 9.0 dBmV 41.2 dB 0 0
10 Locked QAM256 513000000 Hz 8.7 dBmV 41.1 dB 0 0
11 Locked QAM256 519000000 Hz 8.8 dBmV 41.1 dB 0 0
12 Locked QAM256 525000000 Hz 8.3 dBmV 41.1 dB 0 0
13 Locked QAM256 531000000 Hz 8.2 dBmV 40.9 dB 0 0
14 Locked QAM256 537000000 Hz 8.2 dBmV 41.0 dB 0 0
15 Locked QAM256 543000000 Hz 8.0 dBmV 40.8 dB 0 0
16 Locked QAM256 549000000 Hz 7.9 dBmV 40.7 dB 0 0
17 Locked QAM256 555000000 Hz 7.8 dBmV 40.7 dB 0 0
18 Locked QAM256 561000000 Hz 7.9 dBmV 40.7 dB 0 0
19 Locked QAM256 567000000 Hz 7.6 dBmV 40.7 dB 0 0
20 Locked QAM256 573000000 Hz 7.5 dBmV 40.5 dB 0 0
21 Locked QAM256 579000000 Hz 7.7 dBmV 40.7 dB 0 0
22 Locked QAM256 585000000 Hz 7.4 dBmV 40.4 dB 0 0
23 Locked QAM256 591000000 Hz 7.3 dBmV 40.4 dB 0 0
24 Locked QAM256 597000000 Hz 7.1 dBmV 40.3 dB 0 0
25 Locked QAM256 603000000 Hz 6.9 dBmV 40.2 dB 0 0
26 Locked QAM256 609000000 Hz 6.6 dBmV 40.1 dB 0 0
27 Locked QAM256 615000000 Hz 6.4 dBmV 40.0 dB 0 0
28 Locked QAM256 621000000 Hz 6.3 dBmV 39.9 dB 0 0
29 Locked QAM256 627000000 Hz 6.1 dBmV 39.7 dB 0 0
30 Locked QAM256 633000000 Hz 6.0 dBmV 39.6 dB 0 0
31 Locked QAM256 639000000 Hz 5.8 dBmV 39.5 dB 0 0
32 Locked QAM256 645000000 Hz 5.9 dBmV 39.7 dB 0 0
33 Locked QAM256 651000000 Hz 5.7 dBmV 39.6 dB 0 0
34 Locked QAM256 657000000 Hz 5.5 dBmV 39.4 dB 0 0
35 Locked QAM256 663000000 Hz 5.7 dBmV 39.6 dB 0 0
36 Locked QAM256 669000000 Hz 5.4 dBmV 39.4 dB 0 0
38 Locked QAM256 681000000 Hz 5.5 dBmV 39.5 dB 0 0
39 Locked QAM256 687000000 Hz 5.4 dBmV 39.5 dB 0 0
40 Locked QAM256 693000000 Hz 5.5 dBmV 39.4 dB 0 0
159 Locked Other 702000000 Hz 6.6 dBmV 38.5 dB 218280402 0


 

 
Upstream Bonded Channels
Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 3 Locked SC-QAM Upstream 23700000 Hz 6400000 Hz 31.0 dBmV
2 1 Locked SC-QAM Upstream 36500000 Hz 6400000 Hz 32.0 dBmV
3 2 Locked SC-QAM Upstream 30100000 Hz 6400000 Hz 32.0 dBmV
4 4 Locked SC-QAM Upstream 17300000 Hz 6400000 Hz 31.0 dBmV
Date Time Event ID Event Level Description
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=c8:63:fc:a1:49:59;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:49 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:49 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:49 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:48 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:47 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:45 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:45 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:44 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:43 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:42 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:42 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:42 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:28 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:27 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:27 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 09:27 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 08:32 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:01 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:28 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:28 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:28 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:28 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:27 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:27 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:27 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:27 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/23/2020 07:26 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:50 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:50 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:50 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:49 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:49 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:49 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:49 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:49 82000400 3 "Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:47 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:47 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:47 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:47 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:47 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:42 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:42 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:42 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:42 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:42 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:42 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:34 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"
06/22/2020 15:34 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=c8:63:fc:a1:49:59;CMTS-MAC=18:8b:9d:4a:72:41;CM-QOS=1.1;CM-VER=3.1;"

 

Google tells me that I might need an amplifier, but hoping to get expert help from this forum.

 

Thank you!!

Highlighted
Expert

Re: Intermittent dropped connectivity - uncorrectables in downstream and low power in upstream

The signal stat numbers were o/k at that snapshot in time. As a matter of fact, the downstream power is strong, so you don't need an amp. However, the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) somewhere.

 

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

 

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !



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Highlighted
Official Employee

Re: Intermittent dropped connectivity - uncorrectables in downstream and low power in upstream

Hello @hkp703, thanks for reaching out to us on our Forums page. We appreciate you being a customer with us and I'm sorry to hear about the connection issues you have been experiencing. I can imagine how frustrating and inconvenient that must be. I would be more than happy to further troubleshoot and assist you with this. Can you please send me a private message including your first and last name as it appears on the account? 

 

To send me a Private Message, please click my name “ComcastAmira” and click “send a message". 

 


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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.
Was your question answered? Mark the post as Best Answer!
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Regular Visitor

Re: Intermittent dropped connectivity - uncorrectables in downstream and low power in upstream

Thanks! I just PM'ed you.