Connection issues after modem upgrade

I had stable internet with the SB6120 cable modem. After upgrading to SB8200, have intermittent connection issues for months. I replaced SB8200 with a new one but same issues. Also video calls have lag.

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Freq. (MHz)	Pwr (dBmV)	SNR (dB)	Corrected	Uncorrected
1	Locked	QAM256	20	531.0	-1.0	45.5	0	0
2	Locked	QAM256	1	417.0	-0.8	45.6	0	0
3	Locked	QAM256	2	423.0	-0.7	45.8	0	0
4	Locked	QAM256	3	429.0	-0.9	45.6	0	0
5	Locked	QAM256	4	435.0	-1.2	45.5	0	0
6	Locked	QAM256	5	441.0	-0.8	45.7	0	0
7	Locked	QAM256	6	447.0	-0.7	45.7	0	0
8	Locked	QAM256	7	453.0	-0.6	45.8	0	0
9	Locked	QAM256	8	459.0	-0.4	45.8	0	0
10	Locked	QAM256	9	465.0	-0.3	46.0	0	0
11	Locked	QAM256	10	471.0	-0.5	45.7	0	0
12	Locked	QAM256	11	477.0	-0.4	45.6	0	0
13	Locked	QAM256	12	483.0	-0.6	45.7	0	0
14	Locked	QAM256	13	489.0	-0.5	45.7	0	0
15	Locked	QAM256	14	495.0	-0.7	45.7	0	0
16	Locked	QAM256	15	501.0	-0.7	45.6	0	0
17	Locked	QAM256	16	507.0	-1.2	45.4	0	0
18	Locked	QAM256	17	513.0	-1.0	45.5	0	0
19	Locked	QAM256	18	519.0	-1.0	45.5	0	0
20	Locked	QAM256	19	525.0	-1.0	45.5	0	0
21	Locked	QAM256	21	537.0	-1.3	45.5	0	0
22	Locked	QAM256	22	543.0	-1.4	45.3	0	0
23	Locked	QAM256	23	549.0	-1.5	45.1	0	0
24	Locked	QAM256	24	555.0	-1.6	45.1	0	0
25	Locked	QAM256	25	561.0	-1.0	45.3	0	0
26	Locked	QAM256	26	567.0	-1.1	45.3	0	0
27	Locked	QAM256	27	573.0	-0.7	45.5	0	0
28	Locked	QAM256	28	579.0	-0.8	45.5	0	0
29	Locked	QAM256	29	585.0	-0.7	45.4	0	0
30	Locked	QAM256	30	591.0	-0.9	45.3	0	0
31	Locked	QAM256	31	597.0	-0.9	45.3	0	0
32	Locked	QAM256	32	603.0	-0.8	45.3	0	0
33	Locked	OFDM PLC	193	957.0	-2.7	42.8	2360022	0

Upstream Bonded Channels

Channel	Lock Status	Channel Type	Channel ID	Symb. Rate (Ksym/sec)	Freq. (MHz)	Pwr (dBmV)
1	Locked	SC-QAM	1	5120	16.4	49.8
2	Locked	SC-QAM	2	5120	22.8	50.0
3	Locked	SC-QAM	3	5120	29.2	50.5
4	Locked	SC-QAM	4	5120	35.6	50.5

02:05:07 Mon Sep 11 2023		Critical (3)		Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-VER=3.1;
	02:05:07 Mon Sep 11 2023		Critical (3)		UCD invalid or channel unusable;
	02:05:07 Mon Sep 11 2023		Critical (3)		Started Unicast Maintenance Ranging - No Response received - T3 time-out;
	02:05:08 Mon Sep 11 2023		Critical (3)		UCD invalid or channel unusable;
	02:05:09 Mon Sep 11 2023		Critical (3)		Started Unicast Maintenance Ranging - No Response received - T3 time-out;VER=3.1;
	02:05:09 Mon Sep 11 2023		Critical (3)		UCD invalid or channel unusable;
	02:06:07 Mon Sep 11 2023		Critical (3)		Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;C
	02:06:08 Mon Sep 11 2023		Critical (3)		No Ranging Response received - T3 time-out;C
	02:06:09 Mon Sep 11 2023		Critical (3)		Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;C
	02:06:14 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:Fixed Initial, 5-42MHz.
	02:06:16 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
	02:06:16 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
	02:06:17 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
	02:06:22 Mon Sep 11 2023		Critical (3)		No Ranging Response received - T3 time-out;C
	02:06:25 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:Fixed Initial, 5-42MHz.
	02:06:28 Mon Sep 11 2023		Critical (3)		SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;C
	02:06:34 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
	02:06:34 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
	02:06:35 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
	02:06:41 Mon Sep 11 2023		Critical (3)		No Ranging Response received - T3 time-out;C
	02:06:46 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:Fixed Initial, 5-42MHz.
	02:06:50 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
	02:06:50 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
	02:06:51 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
	02:06:57 Mon Sep 11 2023		Critical (3)		No Ranging Response received - T3 time-out;C;
	02:07:05 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:Fixed Initial, 5-42MHz.
	02:07:08 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
	02:07:09 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
	02:07:09 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
	02:07:24 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
	02:07:24 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
	02:07:14 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
	02:07:17 Mon Sep 11 2023		Critical (3)		SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;C
	02:07:31 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
	02:07:31 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
	02:07:31 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change_Ignored:TLV-21.1, 85MHz.
	02:07:32 Mon Sep 11 2023		Critical (3)		UCD invalid or channel unusable;C
	02:07:45 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
	02:07:45 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
	02:07:45 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
	02:07:46 Mon Sep 11 2023		Critical (3)		SYNC Timing Synchronization failure - Loss of Sync;C
	02:07:54 Mon Sep 11 2023		Critical (3)		UCD invalid or channel unusable;C
	Time Not Established		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:Fixed Initial, 5-42MHz.
	Time Not Established		Critical (3)		SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;C
	Time Not Established		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
	Time Not Established		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
	Time Not Established		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-85MHz.
	Time Not Established		Notice (6)		Honoring MDD; IP provisioning mode = IPv6
	Time Not Established		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
	Time Not Established		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
	16:02:06 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
	16:02:07 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
	16:02:07 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
	16:02:07 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change_Ignored:TLV-21.1, 85MHz.
	16:02:08 Mon Sep 11 2023		Critical (3)		UCD invalid or channel unusable;C
	16:02:12 Mon Sep 11 2023		Notice (6)		Honoring MDD; IP provisioning mode = IPv6
	16:02:20 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
	16:02:20 Mon Sep 11 2023		Critical (3)		CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
	16:02:20 Mon Sep 11 2023		Critical (3)		CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
	16:02:27 Mon Sep 11 2023		Notice (6)		DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;C
	16:02:33 Mon Sep 11 2023		Critical (3)		UCD invalid or channel unusable;C

Responses

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BruceW

Gold Problem Solver

•

26.5K Messages

2 years ago

... intermittent connection issues ...

The downstream signals look OK, but the upstream power levels are borderline (too high), consistent with many of the event log entries. Network connection problems like this are often due to poor coax connections or damaged coax cable, usually in or near your home. Running the cable through a surge protector, a defective splitter, or too many splitters can cause signal problems as well. If there is an amplifier in the line make sure it's getting power.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips.

If you can't find the problem or you'd rather have Comcast take care of it and an employee does not respond to your message here, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. It's not likely they can fix the problem remotely. If not, insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit (approx. $100) unless you have their Service Protection Plan ( https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

XfinityRay

Official Employee

•

3K Messages

2 years ago

Hi there, @user_2bc1b8! @BruceW provided some awesome advice above! Were you able to check the coax wire between the wall outlet and the modem to ensure it is finger tight and without damage? Are there any splitters or amplifiers along that line?

Your Home Network

user_2bc1b8

Connection issues after modem upgrade

BruceW

Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.

XfinityRay

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