Santa Barbara, CA - Significant packet loss in route to Netflix
Over the last couple months, Netflix streaming has been a mediocre experience, at best, despite an otherwise consistently stellar internet connection (averaging 300–340 mbps downstream & 30 mbps upstream, with extremely low ping times, as evidenced by the various ubiquitous speed test services out there).
Generally speaking, beginning a Netflix video stream (from a variety of different devices) will begin at a picture quality ranging between 240 to 480p, then gradually improves —here, "gradually" is a very generous term—back to an acceptable range (of up to 4K).
Tracing a route to fast.com (Netflix's own measure of one's approximate connection to their servers) appears to support my perceived experience. While I will continue to perform additional tests over the coming days, based on multiple diagnostic tests run tonight, packet loss is both consistent and sizeable.
*Edit 8/26/18: Diagnostic test results for fast.com removed from this post, for the sake of brevity, as I no longer consider them relevant to this issue.*