Visitor
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7 Messages
Power Levels Causing Random Modem Hard Lockups - DOCSIS 3.1 DRW Violation
Hello,
I am experiencing random hard lockups with my Arris S34 modem (3-4 times over the past week). A physical power cycle temporarily restores service.
I checked my signal levels, and the physical line appears to be delivering an out-of-spec signal, causing a DOCSIS 3.1 Dynamic Range Window violation:
Downstream Power: Coming in very hot, ranging from +5.7 dBmV to +8.8 dBmV across 32 SC-QAM channels. SNR is excellent (40.9 to 44.6 dB) with 0 uncorrectables, meaning the line is clean but too loud.
Upstream SC-QAM Power: Sitting around 36.8 to 37.0 dBmV across 4 channels.
Upstream OFDMA Power: Channel 41 is bottoming out at 28.8 dBmV.
Because the downstream is coming in so hot, my modem is barely transmitting. This creates an 8.2 dB spread between my SC-QAM and OFDMA channels, which violates the 6 dB Dynamic Range Window.
Right before the modem hard-locks, my event logs consistently show:
Warning - RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRWWarning - REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided ValueWarning - Lost MDD TimeoutMultiple
CM-STATUSevent codes 2 and 5 indicating dropped channels.
I am requesting a line technician to check the tap and balance the line (or install an appropriate pad/attenuator), as the continuous DRW violations appear to be crashing the modem's firmware.
Thank you!




XfinityBenjaminM
Official Employee
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3.3K Messages
6 hours ago
@papow Hello! Thank you for reaching out to us here on the Xfinity Forum. We'll be happy to take a closer look at the signal we're sending you to see what is going on. Please send a Direct Message with your full name and address.
To send a Direct Message:
How To: Direct messaging within the forum
[Edited to remove Modmail instructions and add the Direct Messaging instructions]
(edited)
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EG
Expert
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121.2K Messages
6 hours ago
@papow @XfinityBenjaminM
This is not the Reddit Platform. These are the Comcast Community Help Forums. To send the requested information in a private message via this platform;
• Click "Sign In" if that prompt is visible
• Click the "Direct Messaging" icon [Edited to remove link to Direct Messaging]
• Click the "New message" (pencil and paper) icon
• The "To:" line prompts you to "Type the name of a person but don't do that.
Instead, type Xfinity Support there. As you are typing a drop-down list appears.
• Select "Xfinity Support" from the list. An "Xfinity Support" graphic replaces the "To:" line.
• Type your message in the text area near the bottom of the window
• Press Enter or tap the > icon to send it
[Permission from and credit given to BruceW].
(edited)
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