T3 ranging timeouts and SYNC failures - upstream pinned at 49-50 dBmV with Extended Transmit Power - requesting plant/maintenance check

Own equipment, NETGEAR CM3000 (DOCSIS 3.1), modem uptime 14 days. Requesting a signal/plant investigation rather than a modem swap - the modem is not the problem.

Modem event log, Fri Aug 28:

00:28-00:37 - repeated Critical "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing", with CMTS-MAC reported as all zeros

00:29-00:37 - repeated Warning "Lost MDD Timeout"

00:37 - Critical "No Ranging Response received - T3 time-out"

00:56 - Critical "Started Unicast Maintenance Ranging - No Response received - T3 time-out"

Current levels:

Upstream (ATDMA), 4 bonded channels at 16.4 / 22.8 / 29.2 / 35.6 MHz: 49.0, 49.3, 49.3, 49.8 dBmV. Extended Upstream Transmit Power is enabled.

Upstream OFDMA, channel 43 at 36.2 MHz: 44.5 dBmV.

Downstream: +3.0 to +4.1 dBmV, SNR 41.9-42.7 dB across all 32 channels - levels look normal.

Downstream uncorrectable codewords are heavy despite those normal levels: ch19 2367, ch30 2434, ch27 1667, ch4 1054, ch20 1096, ch22 1095, and 16655 uncorrectables on OFDM channel 2 (957 MHz).

The CMTS has also been reassigning my upstream OFDMA profile repeatedly - profile changes logged at 04:54, 04:59, 06:07, 06:08, 06:14, 08:14, 08:19 and 08:24, cycling between profiles 10, 11 and 12.

Good downstream power and SNR combined with high uncorrectables, plus upstream transmit sitting at the top of range with extended transmit power engaged, suggests noise ingress or a bad fitting rather than simple attenuation.

Please have a technician check the drop and the tap, and open a maintenance ticket if levels at the tap are out of spec. Happy to provide the full event log.