MDD Timeout

I have recently started seeing MDD Timeouts messages in my Cable Modem's log every couple of minutes and have experienced frequent dropouts during Zoom/Skype calls around the same time these began showing up. The MDD Timeouts were very rare prior to about two weeks ago. Reading through similar problems on this forum it seems like this problem is often the result of some issue upstream of the modem. The modem is a brand new Arris G36 modem with only one splitter upstream of the modem that was provided by the Comcast installer. I have pasted the upstream and downstream data from the modem in the hopes someone can interpret it and provide some guidance if there is something I need to do or a Comcast issue.

Downstream QAM

Index	Frequency (MHz)	Power Level (dBmV)	SNR (dB)	Modulation	Lock Status
17	489	-9.099998	36.609653	QAM256	Locked
14	471	-5.599998	38.605377	QAM256	Locked
15	477	-6.299999	38.605377	QAM256	Locked
16	483	-6.700001	38.983261	QAM256	Locked
18	495	-15.500000	31.615677	QAM256	Locked
19	507	-14.799999	32.584778	QAM256	Locked
20	513	-13.400002	34.925610	QAM256	Locked
21	519	-12.500000	35.595078	QAM256	Locked
22	525	-9.299999	36.386890	QAM256	Locked
23	531	-9.099998	37.355988	QAM256	Locked

24	537	-10.799999	36.386890	QAM256	Locked
25	543	-9.400002	37.355988	QAM256	Locked
26	549	-8.000000	37.636276	QAM256	Locked
27	555	-7.099998	38.983261	QAM256	Locked
28	561	-7.299999	38.605377	QAM256	Locked
29	567	-8.099998	37.636276	QAM256	Locked
30	573	-8.099998	37.636276	QAM256	Locked
31	579	-10.400002	36.386890	QAM256	Locked
32	585	-9.599998	37.636276	QAM256	Locked
34	591	-13.099998	33.834164	QAM256	Locked

35	597	-13.900002	33.062504	QAM256	Locked
36	603	-9.799999	37.355988	QAM256	Locked
37	609	-11.299999	35.595078	QAM256	Locked
38	615	-13.000000	35.595078	QAM256	Locked
39	621	-12.500000	34.925610	QAM256	Locked
40	627	-11.900002	34.925610	QAM256	Locked
41	633	-11.400002	35.595078	QAM256	Locked
42	639	-11.000000	35.595078	QAM256	Locked
43	645	-11.400002	36.386890	QAM256	Locked
44	651	-11.099998	36.386890	QAM256	Locked

45

657

-11.400002

36.386890

QAM256

Locked

Downstream OFDM

Index	FFT Type	Channel Width (dB)	# of Active Subcarriers	First Active Subcarrier (MHz)	Last Active Subcarrier (MHz)	Avg RxMER Pilot (dB)	Avg RxMER PLC (dB)	Avg RxMER Data (dB)	Power Level (dBmV)	Modulation	Lock Status
33	4K	96	1880	661	754	40	35	34	-13.0	QAM4096	Locked

Upstream QAM

Index	Frequency (MHz)	Power Level (dBmV)	Channel Type	Symbol Rate (KSym/sec)	Modulation	Lock Status
3	30.1	41.020599	US_TYPE_ATDMA	5120 KSym/sec	64QAM	Locked
9	40.5	41.750000	US_TYPE_ATDMA	1280 KSym/sec	64QAM	Locked
4	36.5	41.770599	US_TYPE_ATDMA	5120 KSym/sec	64QAM	Locked
2	23.7	40.770599	US_TYPE_ATDMA	5120 KSym/sec	64QAM	Locked
1	17.3	40.020599	US_TYPE_ATDMA	5120 KSym/sec	64QAM	Locked

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Responses

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EG

Expert

•

113.3K Messages

4 years ago

The downstream power is too low / out of spec, and the SNR's are on the low side / out of spec on some of the channels. 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 !

0

CCDaryl

Problem Solver

•

828 Messages

4 years ago

@IfZenElse

Have you had a chance do any of the trouble shooting steps recommend by the Expert? If so, what corrections have you performed and have you notice any drops since you made those corrections?

10

I

IfZenElse

Visitor

•

5 Messages

@XfinityDaryl ,

Thank you for following up. I did verify the connections and didn't find anything that could be tightened or improved. This is a new house with new cabling and so all of it is in good shape. There is only one splitter between the cable drop in the house and the modem and that splitter was provided by the Comcast service tech. I checked the MDD Timeouts again today and they seem to be happening frequently (25+/hour). Is it time to have a technician come out to investigate?

4 years ago

0

CCDaryl

Problem Solver

•

828 Messages

@IfZenElse

Thank you for sharing that information. Are you experiencing drops while doing other activities such as web surfing, running an application, streaming videos, online gaming, or only when you are using Zoom and Skype?

I no longer work for Comcast.

4 years ago

0

EG

Expert

•

113.3K Messages

@IfZenElse

Yes. Have a tech out to investigate. 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. And if the problem is found to be on their side of the demarcation point, there will not be any charge.

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.

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4 years ago

0

I

IfZenElse

Visitor

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5 Messages

@XfinityDaryl , the drops that were happening earlier included disconnects from my company's VPN, web surfing, Skype/Zoom, etc. I have not noticed any drops during this past week but I have confirmed this morning that the MDD Timeouts appear to be happening regularly (25+ per hour) and so would like to eliminate them as a potential source of instability if it's clear that they are a symptom of power and SNR being out of spec.

4 years ago

0

I

IfZenElse

Visitor

•

5 Messages

@EG Thank you for all your help. I will take your advice to have a tech out to investigate further.

4 years ago

0

Your Home Network

IfZenElse

MDD Timeout

Downstream QAM

Downstream OFDM

Upstream QAM

EG

CCDaryl

IfZenElse

CCDaryl

EG

IfZenElse

IfZenElse

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