SB8200 suddenly not connecting Docsis 3.1 and multiple channels "not locked"

Modem used to connect via Docsis 3.1 but now is only getting 3.0 and I am having intermittent packet drops. Correctable/Uncorrectables are all over the place.

For the channels that do Lock, power and SNR seem to be good, thought it used to be much better. Download speed is currently 20Mbps or less. MUCH lower than expected. Seems to have started happening (about a month ago) either when a recent update was pushed or after a recent major maintenance in the neighborhood that resulted in widespread outages took place.

Information
Standard Specification Compliant	Docsis 3.1
Hardware Version	4
Software Version	AB01.02.053.01_112320_193.0A.NSH

Startup Procedure
Procedure	Status	Comment
Acquire Downstream Channel	651000000 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
37	Locked	QAM256	651000000 Hz	-5.0 dBmV	40.0 dB	0	0
10	Locked	QAM256	483000000 Hz	-5.1 dBmV	39.9 dB	3	0
11	Locked	QAM256	489000000 Hz	-5.2 dBmV	40.1 dB	6	0
12	Not Locked	Unknown	495000000 Hz	-4.8 dBmV	0.0 dB	0	0
13	Not Locked	Unknown	507000000 Hz	-4.7 dBmV	0.0 dB	0	0
14	Locked	QAM256	513000000 Hz	-4.9 dBmV	0.0 dB	15722	0
15	Locked	QAM256	519000000 Hz	-5.2 dBmV	29.2 dB	8333	0
16	Not Locked	Unknown	525000000 Hz	-4.5 dBmV	0.0 dB	0	0
17	Not Locked	Unknown	531000000 Hz	-4.8 dBmV	0.0 dB	0	0
18	Not Locked	Unknown	537000000 Hz	-4.6 dBmV	0.0 dB	0	0
19	Not Locked	Unknown	543000000 Hz	-4.7 dBmV	0.0 dB	0	0
20	Locked	QAM256	549000000 Hz	-4.7 dBmV	26.9 dB	4763769	39888
21	Not Locked	Unknown	555000000 Hz	-4.6 dBmV	0.0 dB	0	0
22	Locked	QAM256	561000000 Hz	-4.9 dBmV	33.4 dB	4	0
23	Locked	QAM256	567000000 Hz	-4.4 dBmV	39.6 dB	1	0
24	Locked	QAM256	573000000 Hz	-4.6 dBmV	0.0 dB	50752	0
25	Locked	QAM256	579000000 Hz	-4.2 dBmV	33.1 dB	9	0
26	Locked	QAM256	585000000 Hz	-4.1 dBmV	31.0 dB	35	0
27	Locked	QAM256	591000000 Hz	-4.3 dBmV	27.2 dB	1193183	218
28	Not Locked	Unknown	597000000 Hz	-4.1 dBmV	0.0 dB	0	0
29	Locked	QAM256	603000000 Hz	-4.3 dBmV	30.6 dB	6212906	27276
30	Locked	QAM256	609000000 Hz	-4.5 dBmV	40.0 dB	0	0
31	Locked	QAM256	615000000 Hz	-4.6 dBmV	39.8 dB	0	0
32	Locked	QAM256	621000000 Hz	-5.0 dBmV	37.0 dB	29483	8
33	Locked	QAM256	627000000 Hz	-4.8 dBmV	26.5 dB	586180	1848373
34	Locked	QAM256	633000000 Hz	-5.2 dBmV	38.6 dB	164299	580960
35	Locked	QAM256	639000000 Hz	-5.1 dBmV	26.4 dB	991681	2988029
36	Locked	QAM256	645000000 Hz	-5.0 dBmV	33.5 dB	2885944	5136997
38	Locked	QAM256	657000000 Hz	-4.6 dBmV	40.3 dB	0	0
39	Locked	QAM256	663000000 Hz	-4.6 dBmV	40.1 dB	0	0
40	Locked	QAM256	669000000 Hz	-4.1 dBmV	40.3 dB	0	0
41	Locked	Other	722000000 Hz	-2.9 dBmV	15.2 dB	52693926	657027

Upstream Bonded Channels
Channel	Channel ID	Lock Status	US Channel Type	Frequency	Width	Power
1	1	Locked	SC-QAM Upstream	35600000 Hz	6400000 Hz	54.0 dBmV
2	2	Locked	SC-QAM Upstream	29200000 Hz	6400000 Hz	55.0 dBmV
3	3	Locked	SC-QAM Upstream	22800000 Hz	6400000 Hz	54.0 dBmV
4	4	Locked	SC-QAM Upstream	16400000 Hz	6400000 Hz	55.0 dBmV
5	5	Locked	SC-QAM Upstream	40400000 Hz	3200000 Hz	53.0 dBmV

Responses

EG

Expert

•

111.3K Messages

4 years ago

The upstream power is too high / out of spec. And the downstream power is on the low / weak side. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, kinks, sharp bends, etc.

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

Good luck with it !

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user_4b9ba5

Visitor

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6 Messages

4 years ago

Thanks. I don't know why I didn't think to try the splitter. That's fixed issues for me in the past a couple times. I always keep a couple spares around. I'll try swapping and post if it helps.

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user_4b9ba5

Visitor

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6 Messages

4 years ago

Swapping splitters 'helped' but didn't solve all my issues. I just purchased a couple brand new ones I'll get in a couple days. 1 for now and a new spare. I'll probably check outside filter from the provider to make sure it's not loose while I wait for new ones. I'm at least getting better download speeds now, though still not what it should be. Hopefully brand new splitter will fix issues, otherwise I'll have to get provider out to check the line coming in and tap at the pole.

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user_4b9ba5

Visitor

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6 Messages

4 years ago

New splitter didn't resolve issue. Still having intermittent issues with TV service as well as internet and only achieving Docsis 3.0 connection.

Looks like time for a service call for the outside line.

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EG

Expert

•

111.3K Messages

@user_4b9ba5

Yep !

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.

Good luck !

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4 years ago

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user_4b9ba5

Visitor

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6 Messages

@EG

Yup, I reached out to online chat. Shared my specs and findings. They tried re-provisioning it and updating the bootfile and confirmed they still see an issue. They ran some diagnostics and confirmed it seems to be the outside line coming in so scheduled a tech to come check it out. Though as you mention they're most likely only investigating from the tap at the pole to my residence for now. I would fully expect if they find the issue lies deeper within their infrastructure beyond the tap that they'd handle that escalation and wouldn't be a me problem anymore but more of a neighborhood problem since at that point it wouldn't just be me that's effected by whatever the issue is or the resolution/maintenance to fix it.

Hopefully in a couple days though I can report back what the issue was/is.

4 years ago

0

EG

Expert

•

111.3K Messages

Please do !

.......................

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I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.

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4 years ago

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user_4b9ba5

Visitor

•

6 Messages

4 years ago

Tech came out. Replaced filter and re-terminated connection on Tap at the pole due to suckout.

All channels are now locked and I'm getting docsis 3.1 connection.

Upstream is now within spec for my modem with power between 45 dBmV to 51 dBmV

Startup Procedure
Procedure	Status	Comment
Acquire Downstream Channel	405000000 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
42	Locked	QAM256	405000000 Hz	-2.2 dBmV	38.7 dB	2	0
1	Locked	QAM256	429000000 Hz	-1.7 dBmV	38.8 dB	1	0
2	Locked	QAM256	435000000 Hz	-1.6 dBmV	38.7 dB	5	0
3	Locked	QAM256	441000000 Hz	-1.9 dBmV	38.6 dB	3	0
4	Locked	QAM256	447000000 Hz	-1.6 dBmV	38.8 dB	3	0
5	Locked	QAM256	453000000 Hz	-1.4 dBmV	38.7 dB	3	0
6	Locked	QAM256	459000000 Hz	-1.4 dBmV	38.9 dB	1	0
7	Locked	QAM256	465000000 Hz	-1.3 dBmV	39.0 dB	5	0
8	Locked	QAM256	471000000 Hz	-1.6 dBmV	39.0 dB	0	0
9	Locked	QAM256	477000000 Hz	-1.6 dBmV	38.9 dB	4	0
10	Locked	QAM256	483000000 Hz	-1.6 dBmV	38.7 dB	1	0
11	Locked	QAM256	489000000 Hz	-1.7 dBmV	39.1 dB	3	0
12	Locked	QAM256	495000000 Hz	-1.4 dBmV	36.9 dB	3	0
13	Locked	QAM256	507000000 Hz	-1.4 dBmV	38.5 dB	0	0
14	Locked	QAM256	513000000 Hz	-1.4 dBmV	39.0 dB	2	0
15	Locked	QAM256	519000000 Hz	-1.5 dBmV	38.6 dB	3	0
16	Locked	QAM256	525000000 Hz	-1.3 dBmV	38.0 dB	3	0
17	Locked	QAM256	531000000 Hz	-1.4 dBmV	38.5 dB	3	0
18	Locked	QAM256	537000000 Hz	-1.0 dBmV	39.0 dB	6	0
19	Locked	QAM256	543000000 Hz	-1.1 dBmV	39.0 dB	2	0
20	Locked	QAM256	549000000 Hz	-1.0 dBmV	39.0 dB	2	0
21	Locked	QAM256	555000000 Hz	-0.9 dBmV	39.1 dB	3	0
22	Locked	QAM256	561000000 Hz	-1.1 dBmV	39.0 dB	6	0
23	Locked	QAM256	567000000 Hz	-0.7 dBmV	39.2 dB	4	0
24	Locked	QAM256	573000000 Hz	-0.7 dBmV	39.0 dB	6	0
25	Locked	QAM256	579000000 Hz	-0.4 dBmV	39.1 dB	0	0
26	Locked	QAM256	585000000 Hz	-0.4 dBmV	39.2 dB	0	0
27	Locked	QAM256	591000000 Hz	-0.5 dBmV	39.3 dB	4	0
41	Locked	Other	722000000 Hz	0.5 dBmV	37.8 dB	84563982	0
43	Not Locked	QAM256	0 Hz	0.0 dBmV	38.8 dB	1	0
44	Locked	QAM256	411000000 Hz	-2.0 dBmV	39.0 dB	2	0
45	Locked	QAM256	417000000 Hz	-1.8 dBmV	39.1 dB	4	0

Upstream Bonded Channels
Channel	Channel ID	Lock Status	US Channel Type	Frequency	Width	Power
1	1	Locked	SC-QAM Upstream	35600000 Hz	6400000 Hz	50.0 dBmV
2	2	Locked	SC-QAM Upstream	29200000 Hz	6400000 Hz	51.0 dBmV
3	3	Locked	SC-QAM Upstream	22800000 Hz	6400000 Hz	50.0 dBmV
4	4	Locked	SC-QAM Upstream	16400000 Hz	6400000 Hz	51.0 dBmV
5	5	Locked	SC-QAM Upstream	40400000 Hz	3200000 Hz	49.0 dBmV

2

0

CCAbbie

Problem Solver

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1.4K Messages

@user_4b9ba5 Hello! I am glad to hear you were able to get a tech scheduled. Please let us know how the appointment goes and let me know if you need any assistance from me!

I no longer work for Comcast.

4 years ago

0

EG

Expert

•

111.3K Messages

@user_4b9ba5

The upstream power is still too high..... There is no wiggle room to allow for the inevitable fluctuations. Needs more work... 40 to 45 is the preferred range. Hope things stay stable for you. Good luck !! 🙂

I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.

Was your question answered? Please mark an Accepted Answer! tick

4 years ago

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Your Home Network

user_4b9ba5

SB8200 suddenly not connecting Docsis 3.1 and multiple channels "not locked"

EG

user_4b9ba5

user_4b9ba5

user_4b9ba5

EG

user_4b9ba5

EG

user_4b9ba5

CCAbbie

EG

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