Interesting! However, like I mentioned a few posts earlier, I used to have Hyperoptic, and got ~800Mb/s consistently and never had any troubles. If the above applied to my system, I would not have had such fast speeds eith Hyperoptic.
I think everything being known-good with Hyperoptic is probably pretty decisive. I agree there's a lot of weird behaviour being observed and evidenced.
The big picture view is that if 100 Mbps is good enough for daily usage, it might be fine to live with until the root cause reveals itself. Typically such root causes can be obvious in hindsight. It's pretty likely that if one device can achieve 450 Mbps, others should be able to get close to that, especially if it's been seen before with another ISP and their hardware.
I actually saw some weird speedtest-cli behaviour which previously I was ignoring but might look into further because of this thread. I currently get speedtest-cli v2.1.3 download measurements of sub 1 Mbps on wired 1 GbE which is sufficiently laughable to not be worth debugging (fastcom shows 84.64 Mbps with all tests using a Python venv and fresh pip installs).
(bwvenv) [x@x bwtest]$ time speedtest-cli --server 23344 --share; date
Retrieving speedtest.net configuration...
Testing from EE (109.249.187.x)...
Retrieving speedtest.net server list...
Retrieving information for the selected server...
Hosted by 31173 Services AB (London) [35.30 km]: 1200039.52 ms
Testing download speed................................................................................
Download: 0.69 Mbit/s
Testing upload speed......................................................................................................
Upload: 41.28 Mbit/s
Share results:
http://www.speedtest.net/result/14224550928.png
real 0m12.237s
user 0m0.470s
sys 0m0.231s
Wed 18 Jan 09:09:07 GMT 2023
(bwvenv) [x@x bwtest]$ time fastcom --quiet
Max speed: 84.64 Mbps
Mean speed: 63.31 Mbps
real 1m2.256s
user 0m2.150s
sys 0m1.047s
(bwvenv) [x@x bwtest]$ date
Wed 18 Jan 09:11:26 GMT 2023
(bwvenv) [x@x bwtest]$ speedtest-cli --version; date
speedtest-cli 2.1.3
Python 3.6.8 (default, Sep 10 2021, 09:13:53) [GCC 8.5.0 20210514 (Red Hat 8.5.0-3)]
Wed 18 Jan 10:22:52 GMT 2023