High Uncorrectable Packet Loss while Gaming

I'm getting intermittent packet loss and disconnects. Online games show "Reconnecting" several times per session. I've already ruled out my home network, and the loss starts on the Comcast side:

• Pathping: 0% loss to my router, then 13–16% loss starting at the first Comcast hop (po-51-rur302.frederick.md.bad.comcast.net, 68.87.131.137), carrying through every hop after that.
• Modem (Netgear CM700) signal levels look normal: downstream power +3.4 to +4.9 dBmV, SNR 40–43 dB, upstream power 45–46.5 dBmV, all 32 downstream and 4 upstream channels locked.
• But uncorrectable errors are high: 2,600–6,100 per downstream channel after only about 2 days of uptime. This suggests intermittent noise or ingress on the line.
• Outdoor wiring: the line enters through an old, weathered outdoor 2-way splitter with oxidized connectors. One output is unused.