U

Visitor

 • 

2 Messages

Tuesday, November 1st, 2022 9:38 PM

T3 Time-out

I have frequent T3 Timeouts during the day and it causes interruption in service.  Based on other chats in the Forum, I believe I have an issue somewhere in the local neighborhood or outside my home.  I have a Motorola MB8600 DOCSIS 3.1 Cable Modem

 

 

I read through this forum post and it seemed to reflect the same experience I’m having.  https://forums.xfinity.com/conversations/your-home-network/mdd-timeout/621fa524aef5c36d133d413c

 

I leveraged some of the recommendations on troubleshooting and have eliminated all of the splitters within the house. 

 

Below is a screenshot of my upstream and downstream connection

 

Downstream Bonded Channels

  Channel

Lock Status

Modulation

Channel ID

Freq. (MHz)

Pwr (dBmV)

SNR (dB)

Corrected

Uncorrected

   1

Locked

QAM256

32

573.0

11.3

42.3

0

0

   2

Locked

QAM256

17

477.0

10.0

42.1

0

0

   3

Locked

QAM256

18

483.0

9.4

41.9

0

0

   4

Locked

QAM256

19

489.0

9.4

41.8

0

0

   5

Locked

QAM256

20

495.0

10.1

42.2

0

0

   6

Locked

QAM256

21

507.0

9.9

42.1

0

0

   7

Locked

QAM256

22

513.0

9.6

41.9

0

0

   8

Locked

QAM256

23

519.0

9.7

41.9

0

0

   9

Locked

QAM256

24

525.0

9.7

41.9

0

0

   10

Locked

QAM256

25

531.0

10.1

42.0

0

0

   11

Locked

QAM256

26

537.0

10.5

42.3

0

0

   12

Locked

QAM256

27

543.0

10.5

42.2

0

0

   13

Locked

QAM256

28

549.0

10.8

42.2

0

0

   14

Locked

QAM256

29

555.0

10.6

42.1

0

0

   15

Locked

QAM256

30

561.0

11.0

42.2

0

0

   16

Locked

QAM256

31

567.0

11.5

42.5

0

0

   17

Locked

QAM256

33

579.0

11.6

42.3

0

0

   18

Locked

QAM256

34

585.0

11.7

42.4

0

0

   19

Locked

QAM256

35

591.0

11.6

42.4

0

0

   20

Locked

QAM256

36

597.0

11.6

42.3

0

0

   21

Locked

QAM256

37

603.0

11.7

42.4

0

0

   22

Locked

QAM256

38

609.0

11.3

42.1

0

0

   23

Locked

QAM256

39

615.0

11.7

42.3

0

0

   24

Locked

QAM256

40

621.0

12.0

42.4

0

0

   25

Locked

QAM256

41

627.0

11.8

42.4

0

0

   26

Locked

QAM256

42

633.0

11.9

42.3

0

0

   27

Locked

QAM256

43

639.0

12.1

42.4

0

0

   28

Locked

QAM256

44

645.0

11.7

42.2

0

0

   29

Locked

QAM256

45

651.0

11.9

42.2

0

0

   30

Locked

QAM256

46

657.0

11.9

42.1

0

0

   31

Locked

QAM256

47

663.0

12.3

42.5

0

0

   32

Locked

OFDM PLC

48

722.0

13.6

41.8

2776673

0

My Modem shows an event log that looks like this every time I see a connection disruption. 

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;;CM-QOS=1.1;CM-VER=3.1;

No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.1;
Honoring MDD; IP provisioning mode = IPv6
DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-QOS=1.1;CM-VER=3.1;

 

 

Accepted Solution

XfinityGina

Official Employee

 • 

746 Messages

3 months ago

Definitely! Thank you for letting us know you checked the coax too, @user_aa1a37 :) 

 

Please send us a direct message, using the following instructions, and we'll get that technician visit scheduled for you:

(Full credit to @BruceW for this excellent explanation and @Again for the picture!) 

"Search for Xfinity Support" won't work. To send a "Direct Messaging" message to Xfinity Support:

 • Click "Sign In" if necessary

 • Click the "Direct Messaging" icon:

 

 

or https://forums.xfinity.com/direct-messaging

 • Click the "New message" (pencil and paper) icon

 • The "To:" line prompts you to "Type the name of a person". Instead, type "Xfinity Support" there

 •  - As you are typing a drop-down list appears. Select "Xfinity Support" from that list

 •  - An "Xfinity Support" graphic replaces the "To:" line

 • Type your message in the text area near the bottom of the window

 • Press Enter to send it

See https://forums.xfinity.com/conversations/email/cant-create-a-new-email-address/605e52b726aa974d63032d02?commentId=606107ea738c7f46a02b830e for an example.

 

XfinityGina

Official Employee

 • 

746 Messages

3 months ago

Thank you so much for all the information @user_aa1a37, I'm sorry to hear that you're having this trouble! 

 

Our brilliant Expert @EG gave a lot of troubleshooting tips in the post you linked:

 

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 !

 

Have you tried any of the steps outside of eliminating the splitters? If so, please let us know!

(edited)

Visitor

 • 

2 Messages

3 months ago

I did.  I don't have any splitters connected and I have not found any nicks in the coax.  Any way to have a tech check? \

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