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

[hkp703]

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!!

[EG]

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 !

[ComcastAmira]

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". 

[hkp703]

Thanks! I just PM'ed you.