Recurring internet connection and speed issues, need engineer to check tap or line side

Download speed is often far below the 2000 Mbps plan, and the modem points to a line fault impacting downstream channels 29 to 31 (frequencies in range of 620 to 632 MHz). I use a Netgear CM2050V modem on the router's 2.5 Gbps port. 

History. This problem has recurred weekly since May. I have had countless tech chats to restart/reprovision my modem remotely and 5+ field technician appointments, each suggesting a different issue or fix. Several visits landed on rainy days or the days after rain, including my most recent visit on Sep 4. On rainy days no speed problem or channel errors were present, so the technicians found nothing. My logged failures are on dry days (see below, no rain for 8-13 days before Oct 23 to 29 readings below). Since May, I have had new coax runs installed inside my home at my own expense, tried an Xfinity XB8 as well as purchased a new customer-owned CM2050V modem at my own expense, and had new coax laid from the tap to my home at Xfinity's expense. Performance gets better for a few days, but the problem has continued to recur through every one of them. My neighbor who shared the same tap was having similar low speed issues which. They moved to another provider after their issues were not resolved during field tech visits. 

Speeds. Of 46 speed tests from Sep 14 to Oct 29, 34 were under 25% of plan (500 Mbps). None reached 1000 Mbps and the best was 875 Mbps. My speeds are getting worse: the 24 tests since Oct 24 range from 32 to 304 Mbps (2% to 15% of plan), and every test from Oct 27 to 29 was between 32 and 80 Mbps. Upload is normally 270 to 298 Mbps, so the problem is download.

Modem readings (Sample, taken Oct 23 to Oct 29). These data are representative of what has been recurring since May 2026. 

- Channels 29, 30, 31 (620-632 MHz) keep failing. These channels frequently lose lock and SNR drops to 25.7-30.5 dB. All other channels stay near 40 dB or better 

- Uncorrectable errors on channels 29 to 32 passed 3.4 billion in 5 days! After restart Oct 28, they reached 876 million in nine hours!

- Bursts of QAM/FEC lock failures (ex.10 in 2 min Oct 28, 5 in 5 min Oct 29), repeated MDD timeouts, Partial Service on Oct 29

- Power cycling no longer helps: after Oct 28 restart, download speed was 32 Mbps. Restarts sometimes gave relief but not for more than a few minutes or hours when they do seem to help. 

Weather. Rain appears to be a factor. Speeds and modem channel readings are GREAT and ERROR FREE on RAINY days, sometimes lasting 1 to 2 days after rain. Speeds and channel readings are POOR on DRY days (30 to 71°F, with no rain in the 13 days before Oct 23 to 29).

Request. Escalation to network engineering or plant maintenance to inspect the tap, node and channels at 620 to 632 MHz upstream of my home, since equipment and home wiring have been replaced without effect.