When accessing my droplet from my home (Comcast) network I get a maximum of 6 megabits/second throughput, sometimes significantly less.

My home cable connection is 90 megabits/sec, verified using speedtest.net to several different servers NOT in Comcast's network.

When I run the speedtest.net cli tool on my droplet I get 120 Mbit/sec to local New York servers, confirming that Digital Ocean has a fast backbone connection.

When I run the speedtest.net tool from my droplet to the Comcast server in my area (server ID 1780) I get upload (droplet->client) speeds around 27 Mbit/sec, which isn't great but still 4-5 x faster than what I see end-to-end.

Traceroutes and pings in both directions look OK.

Is there a way to diagnose the very low bandwidth end-to-end?