Intermittent Upstream Connection Drops / Critical SYNC Failures & High Uncorrected Blocks on Motorola MB7420

Subject: Intermittent Upstream Connection Drops / Critical SYNC Failures & High Uncorrected Blocks on Motorola MB7420

Hello, Xfinity technical support

I am experiencing severe, intermittent network freezes and connection drops where my entire upstream internet traffic completely stalls and chokes. I am posting here because my connection diagnostics point directly to an outside physical infrastructure issue on the Xfinity street line.

I own a standalone Motorola MB7420 cable modem. Because I am using customer-owned equipment, I am unable to use the automated in-app speed tests, but my internal modem diagnostic pages show definitive proof of severe physical line issues:

 1. Maxed Out Upstream Power: My Upstream Bonded Channels are currently locked as high as 48.7 dBmV. My modem is transmitting at maximum capacity just to push data past heavy resistance on the line, leaving zero safety margin for normal daily fluctuations.

2. High Uncorrected Block Errors: My Downstream Bonded Channels show a severe level of packet corruption, specifically on Channels 14 and 15, which have logged over 19,000 Uncorrected Blocks. Physical line noise is actively destroying data packets before they can be processed.

3. Critical Modem Event Logs: My event log has recorded multiple Critical (3) SYNC Timing Synchronization failures (specifically failing to acquire QAM/QPSK symbol timing and FEC framing) along with Critical T3 Timeouts.

Since my local coaxial connections are tightly secured, my internal Ethernet cables are brand new, and the hardware has been completely cleared, this data mathematically proves there is heavy signal ingress, a degraded drop line, or an unbalanced tap outside my home.

I need an official Xfinity to help schedule a physical line technician to inspect the street tap, balance the upstream transmit signals, and pull my upstream power levels back down into a healthy specification.

• Charge Confirmation: Since the diagnostic metrics explicitly isolate this as an infrastructure failure outside my property boundary, please confirm in writing via my account email address that there will be $0 cost or trip fees charged to my account for this outside maintenance.
• Pre-Visit Notification: If the dispatched technician requires entry into my property or needs to meet with me directly, please ensure the system sends a direct notification to my account email address at least 3 business days prior to the scheduled inspection date.

Thank you.