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Subject: Mid-Split Infrastructure Issue: Persistent DRW Mismatch and T3 Timeouts on Brand-New Netgear CM2500
Hello,
I need an escalation to Tier 3 Advanced Support or Line Maintenance (Bucket Truck Crew) for a persistent upstream plant/node configuration issue.
A field technician visited this morning, cleared my premises lines, and isolated the intermittent WAN dropouts to my modem hardware. Following their advice, I completely replaced the unit with a brand-new Netgear CM2500 at Best Buy.
Within minutes of provisioning the new modem via the Xfinity app, the exact same RF layer collapse, Dynamic Range Window (DRW) violations, and TCS Partial Service flags recurred on the identical neighborhood CMTS. This completely rules out my local hardware and confirms a node or plant-side defect.
Below is the engineering data from the newly provisioned modem:
New Modem MAC: [Edited: "Personal Information"]
Target CMTS-MAC: [Edited: "Personal Information"]
Target CMTS-MAC: [Edited: "Personal Information"]
POST-PROVISIONING EVENT LOG (Oct 21):
- 10:04:38 AM - Notice (6) - TLV-11 - unrecognized OID
- 10:04:59 AM - Warning (5) - Dynamic Range Window violation / RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW
- 10:05:42 AM - Warning (5) - TCS Partial Service
- 10:05:56 AM - Critical (3) - No Ranging Response received - T3 time-out
- 10:06:12 AM - Warning (5) - DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value
DIAGNOSTIC ANALYSIS:
- DBC-REQ Mismatch (P1.6hi vs CCAP): The mid-split node profile instructions are sending conflicting upstream parameters to the modem during handshakes, indicating a provisioning or software configuration error on the CMTS side.
- DRW / Commanded Power Violations: The CMTS is commanding an upstream transmit power allocation that violates the mathematical boundaries of the DOCSIS 3.1 Dynamic Range Window, likely due to severe physical attenuation or an incorrect power profile at the street tap.
- T3 Timeouts & TCS Partial Service: The return path is collapsing, forcing the modem into partial service, dropping upstream channels, and causing severe WAN packet loss across my entire network.
Because the on-site technician already verified my local lines and the hardware has been completely swapped, please do not schedule another basic residential tech visit. I request that an advanced support agent pull the historical CMTS flapping logs for my new MAC address and open a formal Line Maintenance ticket to check the node configuration and neighborhood plant for ingress noise or profile mismatches.
Thank you.
[Title edited: "Personal Information"]
XfinityAirelle
Official Employee
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3.6K Messages
23 hours ago
We appreciate the detailed technical information you've provided, especially the event logs from your newly installed Netgear CM2500. We can see you've already taken extensive steps to isolate the issue, including having a technician inspect your premises wiring and replacing your modem entirely.
The fact that you're seeing the same T3 timeouts, Dynamic Range Window violations, and partial service warnings on two different modems is significant. While this doesn't conclusively establish a node or CMTS issue, it certainly warrants looking beyond the original equipment.
We understand you're requesting an investigation into the upstream signal conditions, CMTS configuration, and potential network maintenance concerns rather than another routine technician visit.
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