I need technical support for an intermittent wired Internet/DOCSIS issue, not Wi-Fi troubleshooting

I have a computer connected by Ethernet that continuously monitors my Internet connection. My normal download tests are approximately 500–600 Mbps, but today for approximately 6 hours, wired download performance dropped as low as roughly 20–60 Mbps. My monitoring also recorded a packet-loss spike above 20%. Upload performance has been much more consistent. This pattern repeats sporadically. 

I have also discovered that a significant portion of the Xfinity coax service drop outside my house is exposed above ground.

My XB8 is in bridge mode, and Xfinity's current interface prevents me from accessing its DOCSIS channel/signal statistics.

I need help to check the XB8's historical downstream/upstream signal levels and error history and arrange for a technician to inspect the outside drop, connectors, and signal levels. I do not want to reboot the gateway before those diagnostics are checked because the problem is intermittent and I don't want to clear useful diagnostic information.