Ask HN: How to find the network bottleneck to my cloud storage provider?

I recently signed up for a lifetime plan with PCloud EU. I used their integrated speed test because the speed is erratic and unusable at its worst. PCloud support directed me to my ISP but they haven’t been helpful beyond asking me to reset my equipment. The connection is just as slow on my fast work connection with a different ISP. Speedtest.net to other servers in the same country (Luxembourg) are fine from both home and work connections. Is there something like traceroute that can measure the speed (Mbps) for each hop, or a better way to see where the bottleneck is?