Yes, it looks like typical head-of-line blocking with a multi-second
buffer. To smooth it out, you would need an averaging window wider than
the effective (bloated) RTT.
A tell-tale symptom is that the width of the gap, in which little or no
progress is made at the application layer, is
Is this classic buffer bloat on 50 megabit cable modem?
https://www.dslreports.com/forum/r31035315-Weird-speed-test-results-It-falls-off-right-at-the-end
by extending the download duration to 30 seconds, what looks like
a speed "fall-off at the end" reveals two complete stall/recoveries, and
