No, I do not have a solution yet. From 3pm-after midnight, my connection is unusable: under 0.5Mbps. I performed the tests per your instructions (and more).
Here is my test data again. The testmy url is below the data in this email. Thank you for your help!
Test Environment:
HT2000w: wifi SSIDs disabled - 2GHz disabled, 5GHz disabled, 1 laptop directly connected to HT2000w by ethernet cable
Laptop: Windows10, Chrome browser
Weather: clear
Location: 14505 Stetson Road Los Gatos, CA 95033 - about 20 miles south of San Jose/SiliconValley.
1 8:16 20Mbps 0.21Mbps
2 8:19 27 0.16
3 8:24 26 0.29
4 8:32 16 0.19 4.79Mbps
5 8:37 10 0.17 2.86
Netflix test: 5min to load before start, heavily pixelated, rebuffer at 2:30m, loading indicator, gave up
9/13/17 - following morning to my prior tests
Weather: cloudy, light rain
# Time(PDT) testmy.net HN Speed Test speedtest.xfinity.com
1 8:11am 32Mbps 38Mbps 37Mbps
2 8:16am 45 40 44
3 8:21am 43 20 30
4 8:26am 45 20 44
5 8:31am 45 29 41
Several "share your results" url's are surfacing in the testmy.net ui so I'm not sure which one of these is right.