Intermittent internet drops every few minutes – packet loss between gateway and CMTS, upstream OFDMA channels not locked

Hi,

Since around October 7, my home internet has been dropping every few minutes. Each drop lasts about 1–2 minutes, then the connection comes back. It affects all devices at the same time. Rebooting the gateway doesn’t help.

On October 9, I contacted support through chat. The agent ran some remote tests and the connection was better for a while afterward, but the same issue came back on October 10. Since the problem is intermittent, automated checks pass whenever the connection happens to be up.

What I’ve found so far:

Local network is fine: ping from my computer to the gateway (10.0.0.1) shows 0% loss, even during the drops.
Loss starts at the gateway-to-CMTS link: pathping shows about 48% loss on the link between my gateway and the first Comcast hop (10.28.130.50 → 96.216.143.177). The hops after that show no loss of their own. 
Upstream: OFDMA channels 50 (105 MHz) and 51 (200 MHz) show “Not Locked.” ATDMA channels 17–20 are locked at about 39–41 dBmV. 
Downstream: SNR is good (46–48 dB), but power is a bit high: +7.5 to +8.3 dBmV on the SC-QAM channels and +10.6 / +12.8 dBmV on the OFDM channels. 
Codewords: uncorrectables are low on the SC-QAM channels; OFDM channel 193 shows a higher number of correctables. 
Timestamped ping log showing repeated timeouts every few minutes

The coax runs directly from the wall to the gateway. There’s no splitter and nothing else I can check on my side.

This looks like a line or node issue rather than anything in my home network. Could someone please check my modem’s T3/T4 timeout and flap history, review the upstream channel status, and make sure the technician knows the issue is intermittent?

Thanks!