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Motorola SB6120 constant T3/T4 timeouts and reboots

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Motorola SB6120 constant T3/T4 timeouts and reboots

My Motorola 6120 modem keeps rebooting many times a day, log shows T3/T4 timeouts.
Modem is several years old, but was little used, and never had issues before.  For last few weeks it reboots happen many times a day. Any ideas what's wrong?

 

I see smilar issue reported at:

https://forums.xfinity.com/t5/Internet-Archive/Constant-T3-and-T4-Timeouts-even-after-tech-visit/td-...

 

Signal levels:

Downstream Bonding Channel Value
Channel ID 12  16 
Frequency 507000000 Hz  513000000 Hz  537000000 Hz  561000000 Hz 
Signal to Noise Ratio 37 dB  37 dB  38 dB  39 dB 
Downstream Modulation QAM256  QAM256  QAM256  QAM256 
Power Level
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
-4 dBmV   -4 dBmV   -2 dBmV   -3 dBmV  

 

Upstream Bonding Channel Value
Channel ID 64  63  62  61 
Frequency 36700000 Hz  30300000 Hz  23700000 Hz  17300000 Hz 
Ranging Service ID 9746  9746  9746  9746 
Symbol Rate 5.120 Msym/sec  5.120 Msym/sec  5.120 Msym/sec  5.120 Msym/sec 
Power Level 51 dBmV  50 dBmV  51 dBmV  51 dBmV 
Upstream Modulation [2] QPSK
[1] 32QAM
[3] 64QAM
 
[2] QPSK
[1] 32QAM
[3] 64QAM
 
[2] QPSK
[1] 32QAM
[3] 64QAM
 
[2] QPSK
[1] 32QAM
[3] 64QAM
 
Ranging Status Success  Success  Success  Success 

 

Signal Stats (Codewords) Bonding Channel Value
Channel ID 12  16 
Total Unerrored Codewords 215643824  215641194  215632843  215625600 
Total Correctable Codewords 4013  6552  13681  18749 
Total Uncorrectable Codewords 5668  5692  6986  9174 

 

 

Recent Logs:

 

Time Priority Code Message
Jan 14 2019 11:51:22 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:09:33 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:37 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:13 6-Notice N/A Cable Modem Reboot due to T4 timeout ;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:08:18 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:08:16 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:08:16 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:08:15 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:07:47 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:07:47 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:07:47 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:07:21 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:07:21 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:07:20 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:06:45 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:06:45 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 11:06:43 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 09:41:59 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:03:17 5-Warning D04.1 ToD request sent - No Response received;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:02:42 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
---------------------------------------------------
Jan 14 2019 08:43:19 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:43:18 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:43:17 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:42:58 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:42:57 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:42:56 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
----------------------------------------------------
Jan 14 2019 08:44:40 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:44:40 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:44:40 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:44:40 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:44:39 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
----------------------------------------------------
Jan 14 2019 09:41:59 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 09:41:59 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:03:17 5-Warning D04.1 ToD request sent - No Response received;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:02:42 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:13 6-Notice N/A Cable Modem Reboot due to power reset ;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:46:56 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 14 2019 08:46:55 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:01:26 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:01:5c:6e:12:71;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:13 6-Notice N/A Cable Modem Reboot due to T4 timeout ;CM-MAC=e4:83:99:8b:1f:a8;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
--------------------------------------

Expert

Re: Motorola SB6120 constant T3/T4 timeouts and reboots

The upstream power is on the high side and may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems.

In a self troubleshooting 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 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

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.




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New Poster

Re: Motorola SB6120 constant T3/T4 timeouts and reboots

Thanks a lot. I eliminated one of the splitters. Numbers look better, I will update if modem shows timeouts/reboots again.

Downstream Bonding Channel Value
Channel ID 12  16 
Frequency 507000000 Hz  513000000 Hz  537000000 Hz  561000000 Hz 
Signal to Noise Ratio 37 dB  37 dB  38 dB  38 dB 
Downstream Modulation QAM256  QAM256  QAM256  QAM256 
Power Level
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
1 dBmV   1 dBmV   2 dBmV   1 dBmV  

 

Upstream Bonding Channel Value
Channel ID 64  63  62  61 
Frequency 36700000 Hz  30300000 Hz  23700000 Hz  17300000 Hz 
Ranging Service ID 9746  9746  9746  9746 
Symbol Rate 5.120 Msym/sec  5.120 Msym/sec  5.120 Msym/sec  5.120 Msym/sec 
Power Level 46 dBmV  46 dBmV  46 dBmV  46 dBmV 
Upstream Modulation [2] QPSK
[1] 32QAM
[3] 64QAM
 
[2] QPSK
[1] 32QAM
[3] 64QAM
 
[2] QPSK
[1] 32QAM
[3] 64QAM
 
[2] QPSK
[1] 32QAM
[3] 64QAM
 
Ranging Status Success  Success  Success  Success 

 

Signal Stats (Codewords) Bonding Channel Value
Channel ID 12  16 
Total Unerrored Codewords 243054361  243053694  243059186  462937612 
Total Correctable Codewords 16118  18450  23545  29804 
Total Uncorrectable Codewords 45433  43703  33156  35622 
Expert

Re: Motorola SB6120 constant T3/T4 timeouts and reboots

Looks good. Hope this cures your problem !



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? Mark the post as Best Answer!