Installed this modem towards the end of December 2018. January and February have been fine up until about EOD Feb 18. Latency spikes happened for about 12 hours, and it returned to normal. Has been fine for ~3 days and for the past 8 hours and continuing, I'm getting latency spikes again. Restarting the modem does not fix the problem.
Latency tests have been run from multiple computers hardwired directly into the cable modem. I have also replaced the cables, to ensure they weren't faulty.