Thanks for the reply. I downloaded a file from my server (with multiple sources) and got speeds of 50 kilobytes/second. I downloaded a file from another server (it also had multiple sources) and got speeds of 500-1000 kilobytes/second.

I have not done a speed check to determine my upload capacity. Could you recommend a way to do that, and is it done on the server?

The ISPs are all the same, but I suppose the routes could be different.