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S33 modem keeps losing connection to Cox

  • 6 November 2023
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I am constantly losing connection to the internet and see the following errors in the modem logs

CMSTATUS:DS_Diplexer_Mode_Change_Ignored

CMSTATUS:US_Diplexer_Mode_Change

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=6c:13:d5:75:6f:21;CM-QOS=1.1;CM-VER=3.1;

Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=6c:13:d5:75:6f:21;CM-QOS=1.1;CM-VER=3.1;

So far Cox has replaced the line from the pole to the modem, talked to multiple cox agents who have reset the modem and the issues are still happening.

I have also done a reset  via the reset button on the bottom of the modem restoring factory defaults.  over this past weekend I have sections of modem logs missing, it there a limit of how much it will keep?  I have noticed this behavior over the past couple of weeks.

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Best answer by SURFboard Moderator 15 November 2023, 01:15

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The logs are Values read by technicians from the internet provider end, since the logs are what the coaxial cable transmits and the log screen on the router is the translator so can be easily read by them, the coaxial cable is owned by the Internet service provider.If your Event Log is reporting a high volume of errors, this would indicate a potential CMTS signal issue. To troubleshoot these errors, we would like to note the current signal levels being used by your (S33).

Since S33 is just a cable modem we would suggest you to monitor connection 24hrs by connecting device directly to the modem using ethernet cable without router. If still issue persist please follow the steps mentioned on below link to check the cable signal level on your modem interface.

http://arris.force.com/consumers/articles/General_FAQs/S33-Cable-Signal-Levels

SURFboard Community Moderator Team
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I called Arris customer support and they directed me to the same article.  It was determined that my power for the upstream Bonded channels was to low between 38.3 and 40 dBmV.

I scheduled a tech to come out and they added a splitter before the modem to boost the power to 50.3 to 52 dBmV.  Everything was fine until this morning.

At 4:30 AM the CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz followed by SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing happened.  Later in the day we have now had 5 lost connections in 30 minutes and the modem uptime has reset each time.  Logs have the same errors as before.

Lots of 

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW

US profile assignment change

No Ranging Response received - T3 time-out

Dynamic Range Window violation

TLV-11 - unrecognized OID

Is the problem with the modem or do I keep putting in tickets with the ISP?

D

Same exact problem is happening to me, same modem, provider, event log.

I emailed cox and hopefully I'll get a response in the morning, which probably will be them telling me to switch to their modem to solve the issue.

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Userlevel 5
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I called Arris customer support and they directed me to the same article.  It was determined that my power for the upstream Bonded channels was to low between 38.3 and 40 dBmV.

I scheduled a tech to come out and they added a splitter before the modem to boost the power to 50.3 to 52 dBmV.  Everything was fine until this morning.

At 4:30 AM the CMSTATUS:US_Diplexer_Mode_Change:Init, 5-42MHz followed by SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing happened.  Later in the day we have now had 5 lost connections in 30 minutes and the modem uptime has reset each time.  Logs have the same errors as before.

Lots of 

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW

US profile assignment change

No Ranging Response received - T3 time-out

Dynamic Range Window violation

TLV-11 - unrecognized OID

Is the problem with the modem or do I keep putting in tickets with the ISP?

In this case we would suggest to try testing lines using the test modem and monitor connection for next 24hrs. If the test modem works fine you can reach out arris.com/consumersupport if the modem is under warranty to work on this case further.

SURFboard Community Moderator Team

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