Intermittent T3/T4 Timeouts, 90-99% speed throttle, 2-10% packet loss

Even though the signal stats looked o/k at that snapshot in time, the error log entries and a few downstream channels with a large number of uncorrectable bit errors confirm that something is going on. Perhaps there is noise ingress into the line(s) / an impairment somewhere.

There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards.  They can check the CMTS (Cable Modem Termination System) for any real time degradation and / or error reports, see your node / cable plant and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

Hi, @NoNeckNunzio, I'd really like to take a closer look into the signal levels here on our side. Could you please send over a private message with your first and last name, and address for further assistance?

• To send a private message, you may need to:
• Click "Sign In"
• Click the "direct message" icon
• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list which appears. The "Xfinity Support" graphic replaces the "To:" line
• Type your message in the text area near the bottom of the window
• Press Enter to send it

Hi all, 

Just coming back to close the loop for those who might wonder what the outcome was - 

The technician confirmed signal lock was slow and investigated outside the house.  He told me he found a filter on the incoming coax line that was likely the culprit so he replaced it and confirmed proper signal behavior/timing was restored.  While my tests (speed, packets) can be intermittent in behavior they did show 0% packet loss and 360/12mbps on LAN.  So I trust the change in his readings confirmed this was the issue, since I can't be absolutely sure.  Nonetheless I think this is closed for now, unless Xfinity sees something in their readings that I can't. 

@EG thanks for the escalation & time to explain the background, and @XfinityLayla for the quick responses!

Best,

NNN

Now closing this topic...