Connection keeps dropping - high upstream power & uncorrectable errors, need line check

My Xfinity internet has been dropping repeatedly for the past two weeks with high latency, packet loss, and intermittent disconnects. I use my own modem (Hitron CODA) and checked its DOCSIS signal page. The readings point to a line/signal problem: Upstream power is 53.0-55.5 dBmV on all channels (near maximum). Downstream power is -12.0 to -14.8 dBmV (low). Downstream SNR is 35-37 dB on 256QAM channels (borderline). There are high uncorrectable error counts on multiple downstream channels (e.g. 5679, 2180, 1989, 1235), and the OFDM/OFDMA (DOCSIS 3.1) channels are not locking. There are no splitters or amplifiers in my home - the modem connects directly to the wall outlet - so the attenuation appears to be on the outside line, connectors, or the tap. Could someone run a signal check and schedule a technician to inspect the outside cabling and tap? Thank you.