Motorola MB8611 Dropping Connection Several Times A Day... Again

My Motorola MB8611 (which I purchased early last December and which is still on the Xfinity approved modems list) is again dropping the connection several times a day and restarting. I've seen this problem periodically since the end of the year. Sometimes it'll go several weeks without any problems then they'll start up again. I've tried all the usual troubleshooting, and the customer service people aren't able to go beyond their "unplug and restart" script.

Any suggestions? I'm worried that I'm just going to end up having to eat the cost and buy a new modem.

Stats and recent event log are below.

Stats...

Software - Device Information
Cable Specification Version	DOCSIS 3.1
Hardware Version	V1.0
Software Version	8611-19.2.18
Cable Modem MAC Address	xxx
Cable Modem Serial Number	xxx
CM Certificate	Installed
	Prod_19.2_d31

Startup Sequence
Startup Step	Status	Comment
Acquire Downstream Channel	489000000 Hz	Locked
Upstream Connection	OK	Operational
Boot State	OK	Operational
Configuration File	OK
Security	Enabled	BPI+
Downstream Bonded Channels	Connection Status
System Up Time	0 days 00h:03m:58s
Network Access	Allowed
Downstream Bonded Channels
Channel	Lock Status	Modulation	Channel ID	Freq. (MHz)	Pwr (dBmV)	SNR (dB)	Corrected	Uncorrected
1	Locked	QAM256	13	489	3.3	41.2	0	0
2	Locked	QAM256	1	417	3.1	41.3	0	0
3	Locked	QAM256	2	423	3	41.1	0	0
4	Locked	QAM256	3	429	3.2	41.4	0	0
5	Locked	QAM256	4	435	3.4	41.3	0	0
6	Locked	QAM256	5	441	2.9	41.1	0	0
7	Locked	QAM256	6	447	2.8	41.1	0	0
8	Locked	QAM256	7	453	2.9	41.2	0	0
9	Locked	QAM256	8	459	2.8	41.1	0	0
10	Locked	QAM256	9	465	2.9	41	0	0
11	Locked	QAM256	10	471	2.8	41.1	0	0
12	Locked	QAM256	11	477	3.3	41.3	0	0
13	Locked	QAM256	12	483	3.2	41.2	0	0
14	Locked	QAM256	14	495	3.2	41.1	0	0
15	Locked	QAM256	15	507	3.6	41.3	0	0
16	Locked	QAM256	16	513	3.6	41.4	0	0
17	Locked	QAM256	17	519	3.7	41.3	0	0
18	Locked	QAM256	18	525	3.8	41.4	0	0
19	Locked	QAM256	19	531	4.2	41.5	0	0
20	Locked	QAM256	20	537	4.2	41.5	0	0
21	Locked	QAM256	21	543	4.2	41.4	0	0
22	Locked	QAM256	22	549	4.7	41.6	0	0
23	Locked	QAM256	23	555	4.9	41.8	0	0
24	Locked	QAM256	24	561	5.1	41.7	0	0
25	Locked	OFDM PLC	25	690	5.9	41.8	884750	0
26	Locked	QAM256	26	567	5	41.6	0	0
27	Locked	QAM256	27	573	5.1	41.7	0	0
28	Locked	QAM256	28	579	5.2	41.7	0	0
29	Locked	QAM256	29	585	5.3	41.9	0	0
30	Locked	QAM256	30	591	5.3	41.9	0	0
31	Locked	QAM256	31	597	5.1	41.7	0	0
32	Locked	QAM256	32	603	5.4	41.8	0	0
Upstream Bonded Channels
Channel	Lock Status	Channel Type	Channel ID	Symb. Rate (Ksym/sec)	Freq. (MHz)	Pwr (dBmV)
1	Locked	SC-QAM	41	5120	16.3	48.8
2	Locked	SC-QAM	42	5120	22.8	48.8
3	Locked	SC-QAM	43	5120	29.2	48.8
4	Locked	SC-QAM	44	5120	35.6	48.8

And the event log over the past 14 hours since noon ET yesterday.

Date	Time EST (+1 hr for EDT)	Priority	Description
Wed Aug 9 2023	Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=xxx:eb:49;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Wed Aug 9 2023	10:53:26	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=xxx:eb:49;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Wed Aug 9 2023	14:10:06	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=xxx:eb:49;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=xxx:eb:49;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Wed Aug 9 2023	Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Wed Aug 9 2023	17:26:03	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=xxx:eb:49;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Thu Aug 10 2023	0:32:11	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=xxx:eb:49;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=xxx:eb:49;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
Thu Aug 10 2023	0:44:48	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;
Thu Aug 10 2023	0:45:05	Notice (6)	CM-STATUS message sent. Event Type Code: 24; Chan ID: 25; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=xxx;CMTS-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;

Responses

Accepted Solution

U

user_4cc66c

5 Messages

2 years ago

FWIW, getting rid of the MB8611 and switching to the Arris S33 resolved a similar issue for me: https://forums.xfinity.com/conversations/your-home-network/sync-timing-synchronization-failure-multiple-modems-motorola-mb8611-netgear-c6250/64d58726e228f948d8d4e3a1.

Luckily I was still within the return window for 8611; in your position, I'd be pretty upset with Xfinity for introducing the incompatibility that forces you to buy a new modem, and/or with Zoom for not releasing a firmware update to support their product.

0

flatlander3

Problem Solver

•

1.5K Messages

2 years ago

It's not dropping, it's spontaneously rebooting. Looks like fairly often (time not established in your log). At that moment in time in your post, you are running towards the high side on upstream power. You're still OK right then, but you want some head space. Might be drifting a lot higher over time. Outbound power adjusts itself to push signal out. Too high, it will reboot.

Weird signal inflection 441-471 MHz on downstream. That's in spec but it's pointing to an instability acting like a notch filter. A splitter perhaps. In a perfect world, all of your signals are within a dB or two. Most of them are these types of problems if you want to look at it yourself.

https://forums.xfinity.com/conversations/your-home-network/yea-please-fix-your-service-kthxbai/64ca8e5a176e642d0138c752 Old cable installs can be pretty ancient equipment.

3

D

dbroccardo

Visitor

•

1 Message

@flatlander3 Check the updated list of cable modems Xfinity has. They have de-listed this modem (not recommended) due to numerous reports of issues just like yours.

2 years ago

0

U

user_4cc66c

5 Messages

Here's the list, for reference: https://assets.xfinity.com/assets/dotcom/projects_2/my_device/Full-List-of-Compatible-Devices.pdf

I just posted about yet another similar issue with the MB8611: https://forums.xfinity.com/conversations/your-home-network/sync-timing-synchronization-failure-multiple-modems-motorola-mb8611-netgear-c6250/64d58726e228f948d8d4e3a1. This list must have just changed, since when I looked at it before purchasing the modem, the list was a different format and it was still on there! (I swear this was more recently than May 15, when it says it was updated.)

2 years ago

0

flatlander3

Problem Solver

•

1.5K Messages

@dbroccardo Yes.

And if you buy another modem/gateway and plug it in, supported or not to the same line, you will likely have the same signal issues if you don't fix components/aging equipment hanging off that line that are behaving like analog signal filters.

Will you get provisioned and the config file for "plan speed" on unsupported equipment? Probably not. That's a different question.

(edited)

2 years ago

0

BruceW

Gold Problem Solver

•

26.4K Messages

2 years ago

... They have de-listed this modem (not recommended) ...

The MB8611 is not a "recommended" device on https://assets.xfinity.com/assets/dotcom/projects_2/my_device/Full-List-of-Compatible-Devices.pdf, but is still listed as "compatible" in that document for plan speeds "up to 2.33 Gbps".

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.

0

CCXanadu

Retired Employee

•

300 Messages

2 years ago

Hey there @userid_3j4acb ! It looks like there has been a lot of great information here, that's exactly what the forums are for! Did you have a chance to look for any splitters or replace any of the internal wiring in your home? If your coax to the outlet that the modem is connected to has to be wall-fished to be replaced, that would be work that a local electrician or similar would do. I would be happy to run a few checks to ensure your signals are within spec on our side of things. If you'd like to work further on this to gather that information, please send us a direct message.

To send a direct message:

Ensure you are first signed in, then you will see a chat box icon at the top right of your page. Click that or follow this link here: https://forums.xfinity.com/direct-messaging
From there, click the 'New Message' icon. In the 'To' field, type 'Xfinity Support'.
Type your message in the text area that appears at the bottom of the window and hit enter to send. An official employee, such as myself or whoever is first available, will respond.

To expedite your request, we ask that you please include your name, the account holder name (if different), and your full address.

0

Your Home Network

userid_3j4acb

Motorola MB8611 Dropping Connection Several Times A Day... Again

user_4cc66c

flatlander3

dbroccardo

user_4cc66c

flatlander3

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.

CCXanadu

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