Observer

modem T3/T4 reboots weekly

I've done quite a bit of searching through the forums and my own troubleshooting, so I'm reaching out to see what my next steps are.  about once a week my modem will reboot due to T3/T4 timeouts.

 

Services and Equipment:

  • WHDVR
    • 1 DVR (ARRIS DCX3600)
    • 1 HD Box (Technicolor, formerly Cisco)
  • Internet
    • Motorola SB6141 (customer owned)
  • Home Phone
    • ARRIS MTA
  • Miscellaneous Equipment
    • PCT 1-port +15db Amplifier with Active Return
    • TWC provided PoE filter
    • 2-port Splitter (High Quality, not gold plated, RS, or BB)
    • 4-port Splitter (Unbranded Satellite spec, came with the house)
    • RG6 cable inside the house with professional compression connectors and tight/secure connections

Current Cable Connections:

Cable In --> Splitter --> Leg 1: Modem, Leg 2: Amplifier

Amplifier --> PoE --> Splitter --> MTA, DVR, Cable Box, 75ohm Terminator

 

I also had everything connected to the 4-port splitter both with and without the amplifier but signal and power levels were still within “good” range regardless of setup.  Without the amplifier, downstream SNR was 42-45dB and power level was -2 - -3dBmv and upstream power level was 45-48dBmv.  With the amplifier, downstream SNR was 39-42dB and power level was 1-3dBmv and upstream power level was 41-44dBmv.

 

Here’s the modem signal page and logs with my current cabling setup as described above.  The first T3/T4 (bottom of the log) was when everything was connected to the 4-way splitter.  You see the reboot due to power loss when I put a 2-way splitter in and connected the modem to it and the amplifier to the other port going to the 4-way splitter.  Then another T3/T4 reboot occured 6 days later.  The times I notice it rebooting are when I login on my laptop and try going to any webpage and lo and behold, the modem is rebooting, but this may just be coincidence when I notice it.

 

Downstream

Bonding Channel Value

Channel ID

19 

10 

12 

13 

14 

15 

16 

17 

Frequency

669000000 Hz 

615000000 Hz 

627000000 Hz 

633000000 Hz 

639000000 Hz 

645000000 Hz 

651000000 Hz 

657000000 Hz 

Signal to Noise Ratio

37 dB 

37 dB 

37 dB 

37 dB 

37 dB 

38 dB 

38 dB 

37 dB 

Downstream Modulation

QAM256 

QAM256 

QAM256 

QAM256 

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

0 dBmV  

0 dBmV  

0 dBmV  

0 dBmV  

0 dBmV  

1 dBmV  

0 dBmV  

0 dBmV  

 

Upstream

Bonding Channel Value

Channel ID

86 

88 

87 

85 

Frequency

24000000 Hz 

36800000 Hz 

30400000 Hz 

19200000 Hz 

Ranging Service ID

10323 

10323 

10323 

10323 

Symbol Rate

5.120 Msym/sec 

5.120 Msym/sec 

5.120 Msym/sec 

2.560 Msym/sec 

Power Level

39 dBmV 

42 dBmV 

42 dBmV 

42 dBmV 

Upstream Modulation

[3] QPSK
[1] 16QAM
[2] 64QAM
 

[3] QPSK
[1] 16QAM
[2] 64QAM
 

[3] QPSK
[1] 16QAM
[2] 64QAM
 

[3] QPSK
[2] 16QAM
 

Ranging Status

Success 

Success 

Success 

Success 

 

Signal Stats (Codewords)

Bonding Channel Value

Channel ID

19 

10 

12 

13 

14 

15 

16 

17 

Total Unerrored Codewords

426556110 

426564411 

426572594 

426580698 

426545152 

426546127 

426547897 

426546584 

Total Correctable Codewords

11 

12 

48 

51 

10 

Total Uncorrectable Codewords

678 

544 

535 

537 

642 

615 

572 

1450 

 

Time

Priority

Code

Message

Mar 26 2018 06:54:50

6-Notice

I401.0

TLV-11 - unrecognized OID;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 26 2018 06:54:50

5-Warning

Z00.0

MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Jan 01 1970 00:00:16

6-Notice

N/A

Cable Modem Reboot due to power reset ;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;

Mar 25 2018 12:58:09

6-Notice

I401.0

TLV-11 - unrecognized OID;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 25 2018 12:58:09

5-Warning

Z00.0

MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Jan 01 1970 00:00:16

6-Notice

N/A

Cable Modem Reboot due to T4 timeout ;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;

Mar 25 2018 12:57:06

3-Critical

R04.0

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 25 2018 12:56:36

3-Critical

R05.0

Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 25 2018 12:55:57

4-Error

C701.0

DBC-ACK not received;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 25 2018 12:55:57

3-Critical

R05.0

Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 20 2018 16:25:04

3-Critical

R02.0

No Ranging Response received - T3 time-out;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 19 2018 18:42:17

6-Notice

I401.0

TLV-11 - unrecognized OID;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 19 2018 18:42:16

5-Warning

Z00.0

MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Jan 01 1970 00:00:22

3-Critical

R02.0

No Ranging Response received - T3 time-out;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Jan 01 1970 00:00:16

6-Notice

N/A

Cable Modem Reboot due to power reset ;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;

Mar 19 2018 18:40:26

3-Critical

T05.0

SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 19 2018 17:01:17

6-Notice

I401.0

TLV-11 - unrecognized OID;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Mar 19 2018 17:01:17

5-Warning

Z00.0

MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

Jan 01 1970 00:00:17

6-Notice

N/A

Cable Modem Reboot due to T4 timeout ;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;

Mar 19 2018 16:58:08

3-Critical

R04.0

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=38:6b:bb:7f:7b:1f;CMTS-MAC=00:01:5c:89:18:74;CM-QOS=1.1;CM-VER=3.0;

 

8 REPLIES
Established Sharer

Re: modem T3/T4 reboots weekly

A T4 timeout means that the modem lost incoming (DS) signal from the head-end for more than three seconds.  This forces the modem to reset itself and start searching again for the first channel in its assigned list. 

Your upstream signals look good on all four channels, and the DS signal levels are consistant.  However, the decoded SNR looks low, with a 0 dBmV incoming level it should generally be above 40 dB.  This issue could also be caused by a malfunctioning or improperly connected amplifier.  If you own the SB6141 modem, it's still just barely useable but getting a lot of grey hairs.  Probably time to think about purchasing a newer unit with a full-band 108-1002 MHz receiver and 16 or 24 DS channels, such as the Motorola SB7420. 

Observer

Re: modem T3/T4 reboots weekly

The amplifier has 3 ports, power in, signal in, amplified signal out. It’s connected properly and functioning properly as the modem will lock DS/US channels even with an amplified signal and the cable boxes are working as well. If I disconnect the amp, there’s no change except now my power levels on the 4-way splitter drop to -8 to -10dB. Not good for a modem, but ok for a cable box knowing issues will arise eventually. The cable modem is going on 5.5 years old. I doubt the hardware is going bad, but you’re right in that it’s ancient technology at this point. It still works in fact I just bumped my internet speed from 60/5 to 100/10 (for unrelated reasons) and it supports it. If I want to go any higher for speed then I will need a 16/24 channel modem or DOCSIS 3.1 compatible. As for the SNR being “low”, it’s still in the good range and isn’t too low until it starts to hit 34/35 then I will start having problems.

I could try a different modem and see if the issues persist (which I think they will). In the meantime I went back to the following setup:
Cable in —> amplifier —> 4-way splitter —> Modem, MTA, DVR, Cable Box

I did this to try to fix a separate issue I’m having with the cable box at the farthest end of the house having channel tuning difficulties and guide data problems. I know the recommendation is to split the cable in signal immediately and put the modem on one leg then send the signal to everything else, but if I amplify then split, I actually get a better stronger signal to everything than split, amplify, split due to removing a splitter and its inherent dB loss.
Contributor

Re: modem T3/T4 reboots weekly

The SB6141 does have issues with aging electrolytic caps.    You can open the unit up and look for any bulging or leakage.  Failure of some of these cap has been a know source of increased T3/T4 errors. 

 

Replaced my aging SB6141 with a CM600 about a week ago.  The Surfboard had been giving me  perhaps 3 or 4 T3 errors per week.  So far, I see only one T3 error on the CM600. 

Observer

Re: modem T3/T4 reboots weekly

Thanks for the tip on this.  I hadn't heard about it before, but it makes sense as electronics age, capacitors get out of spec and are uable to maintain the tolerances in voltage and current required by other sensitive components.

 

EDIT: I retract my previous statement about doubting the hardware has gone bad.  almost 6 years of continuous use, yeah it could be going bad.

Lead Moderator

Re: modem T3/T4 reboots weekly

Good morning!

 

Please let us know if you decide to change out the modem and what effect it had

on the issues. 

 

Regards,
Julia R.
Spectrum-Social Media Customer Care
Lead Moderator-Community Forums

Observer

Re: modem T3/T4 reboots weekly

It may be a couple weeks before I change out the modem if I decide to do so. So far I'm at 3 days uptime with no T3/T4 errors. I won't know until early next week if I still have a problem. I have noticed a very small increase (no more than 10 per channel) in Total Correctable Words, but can't say I've seen an increase in Total Uncorrectable Codewords.
Observer

Re: modem T3/T4 reboots weekly

just an update, modem uptime of 16.5 days and everything is still working.  No reboots or drops since I last posted.  Only other thing I did was replaced a downstream 4-way splitter with a 3-way splitter.  It's off the other leg of the initial 2-way splitter and downstream of the amplifier.  In theory it shouldn't affect anything.  The other thing that changed was bumping my internet speed from 60/5 to 100/10.  those are the only two things I have changed since the last issue I had.  

Lead Moderator

Re: modem T3/T4 reboots weekly

Good morning @boernerb

 

If you consider the issue resolved please let us know, we can mark your post

as solved.

 

Have a great day!

 

Regards,
Julia R.
Spectrum-Social Media Customer Care
Lead Moderator-Community Forums