Frequent 2–3 Minute Outages Since July 15 — MB8611 / Central District Seattle

Hi all,

Since around July 15, I’ve been experiencing frequent short outages, usually twice a day, lasting about 2 to 3 minutes each. These interruptions have been happening consistently, often around 9AM and 10:00 PM, and are disrupting important business calls and meetings.

The modem logs show:

I’m using a Motorola MB8611 (DOCSIS 3.1). Everything was working perfectly prior to July 15.

What I’ve checked:

• My setup is clean. No splitters, no damaged coax, no unnecessary components.

• Downstream signal is excellent, with high SNR and low power levels.

• Upstream is locked to DOCSIS 3.0 channels only, and I’ve never seen OFDMA (DOCSIS 3.1 upstream) active.

• Modem is on firmware 8611-19.2.18.

• I’ve tried rebooting, factory resetting, and monitoring logs daily.

At this point, I’m confident the issue is on the ISP’s side, likely involving upstream provisioning or instability in the Central District of Seattle (98122). Unfortunately, customer support has not been able to provide a meaningful resolution, and I’m posting here in hopes that someone can help escalate this issue.

Request:

If any Xfinity techs or engineers are available to investigate:

• Can someone review the upstream channel configuration for this node?

• Is OFDMA upstream partially deployed or misconfigured in this area?

• Is there known maintenance activity happening around 10:00 PM or throughout the night bleeding into the morning?

Also, if other users in 98122 or nearby neighborhoods are seeing similar issues, I’d appreciate hearing from you.

Thank you for your time.

p.s. raw logs from the past 24 hours:

Fri Aug 1 2025   Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    09:22:02
Fri Aug 1 2025   Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    18:00:40
Fri Aug 1 2025   Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    03:30:44
Sat Aug 2 2025   Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    03:30:59
Sat Aug 2 2025   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    Time Not Established
  Notice (6)   Honoring MDD; IP provisioning mode = IPv6
    09:00:34
Sat Aug 2 2025   Notice (6)   DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    09:00:43
Sat Aug 2 2025   Critical (3)   UCD invalid or channel unusable;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;
    09:02:16
Sat Aug 2 2025   Notice (6)   CM-STATUS message sent. Event Type Code: 24; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1;