7 Messages
Intermittent drops, repeated MDD message timeout / CM-STATUS Event Type Code 4 on DOCSIS 3.1 OFDM channel
Hi Xfinity team,
I am seeing intermittent WAN drops and repeated cable modem log warnings that appear to correlate with my router reporting WAN state changes. I would like help checking the RF plant / CMTS side for my service.
Equipment:
- Modem: Netgear Nighthawk CM2000
- Cable firmware version: V8.01.02
- Router: TP-Link Archer AX55 Pro
- Current modem time when diagnostics were captured: Thu May 28 16:24:46 2026
The modem remains operational overall:
- Acquire Downstream Channel: 417000000 Hz, Locked
- Connectivity State: OK / Operational
- Boot State: OK / Operational
- Security: Enabled, BPI+
- IP Provisioning Mode: Honor MDD, IPv6 only
The modem event log repeatedly shows warnings like:
MDD message timeout; CM-QOS=1.1; CM-VER=3.1;
These are often followed by:
CM-STATUS message sent. Event Type Code: 4; Chan ID: 193; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.; CM-QOS=1.1; CM-VER=3.1;
Channel 193 appears to be my DOCSIS 3.1 downstream OFDM channel:
Downstream OFDM Channel 1
LockedStatus: Locked
ProfileID: 0, 1, 2, 3
ChannelID: 193
Frequency: 850000000 Hz
Power: -11.42 dBmV
SNR/MER: 40.3 dB
ActiveSubcarrier: 148 ~ 3947
Unerror: 100884714688
Correctable: 91535830673
Uncorrectable: 146375624
The OFDM channel is locked, but the OFDM power looks much lower than the SC-QAM downstream channels, and the corrected/uncorrected counts are very high.
My 32 SC-QAM downstream channels are locked. Power levels are generally around -2.5 to -4.3 dBmV, and SNR is around 43.4 to 45.0 dB. However, all downstream channels show non-zero uncorrectables. Examples:
417 MHz: Power -3.1 dBmV, SNR 44.6 dB, Correctables 3570, Uncorrectables 4157
399 MHz: Power -3.4 dBmV, SNR 44.2 dB, Correctables 8238, Uncorrectables 6523
465 MHz: Power -2.9 dBmV, SNR 44.7 dB, Correctables 5782, Uncorrectables 8490
597 MHz: Power -4.3 dBmV, SNR 43.4 dB, Correctables 1746, Uncorrectables 3105
Upstream bonded channels are locked and seem within a normal range:
16.4 MHz: 42.3 dBmV
22.8 MHz: 43.8 dBmV
29.2 MHz: 44.0 dBmV
35.6 MHz: 44.8 dBmV
40.4 MHz: 45.3 dBmV
10.4 MHz: 43.0 dBmV
The router log around these periods shows repeated WAN state changes such as WAN1_ON / WAN0_OFF, then WAN1_OFF / WAN0_ON, which seems consistent with the modem link briefly degrading or dropping.
Could someone please check the line / node / CMTS history for my modem and look specifically for DOCSIS 3.1 OFDM channel issues, MDD timeouts, uncorrectables, or downstream impairment around channel 193 / 850 MHz?
I can provide the modem MAC address privately if needed. I am intentionally not posting MAC addresses publicly.
XfinityJeffB
Official Employee
•
377 Messages
14 hours ago
Hello user_53yxh3, thank you for reaching out here in our Xfinity Community forum. We appreciate you and your time. To best assist you, we will need some information best kept private.
Please send our team a direct message with your full name, the name listed on the account (if different), and the service address associated with your account, I'd be more than happy to look into this for you.
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