U

Visitor

 • 

1 Message

Wednesday, July 9th, 2025 11:19 PM

Upstream OFDMA Causing T3/T4 Timeouts – Need CMTS Provisioning Fix (Netgear CM3000, 2 Gbps Plan)

After countless hours today with several virtual chats, live on the phone support, and “Tier 2” transfers i’m trying this as a last hopeful resort.

Hi Xfinity Support,

I'm having persistent internet drops that appear directly tied to upstream OFDMA instability. I’ve already had a technician visit, and phone support has stated OFDMA was disabled — but my modem logs and status page show otherwise.


📦 Setup:

  • Modem: Netgear CM3000 (DOCSIS 3.1, Xfinity-approved)

  • Plan: 2 Gbps

  • Connection: Wired and wireless drops

  • Symptoms:

    • Frequent disconnections

    • Event logs full of T3 timeouts, T4 timeouts, and no unicast ranging opportunities

    • Drops correlate with OFDMA Channel locking or flapping


Key Log Indicators:

  • Started Unicast Maintenance Ranging - No Response received - T3 time-out

  • 16 consecutive T3 timeouts

  • Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out

  • OFDMA Channel 1 = Locked

  • OFDMA Channel 2 = Not Locked

  • Profile IDs: 12, 13

  • Power levels around 37.3 dBmV


What I've Tried:

  • Power-cycled modem

  • Factory reset modem

  • Tech visit (confirmed signals look clean)

  • Xfinity phone support says they "disabled OFDMA", but modem is still receiving OFDMA provisioning from CMTS


Request:

I’m requesting that upstream OFDMA be fully disabled at the CMTS level:

  • A new provisioning config file pushed to my modem that excludes OFDMA upstream channels

  • Verification that Profiles 12/13 are no longer being assigned

  • Confirmation from engineering that the CMTS override is in place

No Responses!
forum icon

New to the Community?

Start Here