Regular Visitor
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4 Messages
upstream channels
CM1000 MAC [Edited: "Personal Information"] shows 49.3 dBmV single upstream channel + T3 timeouts. Downstream perfect. Need line trace.
Regular Visitor
•
4 Messages
CM1000 MAC [Edited: "Personal Information"] shows 49.3 dBmV single upstream channel + T3 timeouts. Downstream perfect. Need line trace.
Accepted Solution
user_sd216
Regular Visitor
•
4 Messages
5 months ago
Xfinity tech visited ~8AM Feb 20, 2026 and resolved your connectivity issues at the drop.
Tech Actions (Point of Entry)
Removed MoCA/POE filter: Blocks neighbor MoCA signals (1125-1675 MHz) from entering your coax. This filter was blocking your upstream channels 2-4 (22-35 MHz), forcing single-channel operation at max 49.3 dBmV transmit power.
Removed ground strap/block: Corroded lightning arrestor at house entry was injecting RF ingress noise into return path, causing T3 timeouts and UCD errors.
Technical Result
BEFORE: 1 upstream channel @ 49.3 dBmV + 50x T3 errors in 11 minutes AFTER: 4 upstream channels @ 44-48 dBmV + 22+ hour uptime, zero errorsEngineering Summary
The filter prevented proper DOCSIS upstream bonding while the ground block created noise ingress. Both drop-side issues now eliminated. Your CM1000 delivers textbook performance: perfect 9-10 dBmV downstream, optimal 44-48 dBmV upstream across 4 bonded ATDMA channels.
Issue fully resolved—local ingress was sole culprit, not Comcast plant. 22-hour uptime confirms stability.
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