I got SFTP set up on my server, a standard setup following D.O. tutorials. It works properly with FileZilla, WinSCP etc, but won't move above 40kbps, where both the server and the client have a ton of bandwidth. How do I fix this? We need at least 5mbps.
There is no inherent restriction on bandwidth in the default SFTP service. I would recommend checking that your droplet can connect elsewhere and see good throughput (possibly with speedtest-cli or using wget to pull down a file). If you see slow speeds there as well I would recommend that you open a ticket with our team.
If you only see this between your location and your droplet I would also recommend opening a ticket as this could indicate a routing issue between our data center and your ISPs network.