Solution to slow FTP upload on foreign servers (host of site5)

I recently purchased server space from site5.com, with a ping value of around 230ms. The download speed using Thunder can reach over 200KB, and HTTP direct download is around 60KB/S (site5 has a demonstration website site5demo.com, with an http download speed of up to 300KB/S, which is really ideal. Unfortunately, the server is full, and the ping value is only around 130ms).
I found a problem during use, that is, uploading files with flashfxp is very slow. It can reach 60KB at the beginning, but it will be downloaded from 60KB to 0 after dozens of seconds, and finally it will be uploaded slowly, with only a few KB. It took one night to upload only a few MB, which was extremely annoying.
Later I downloaded leapftp3.0.1, but the upload was still very slow. I suddenly thought, why not try the PORT active mode. It is easier to adjust in LeapFtp. "Preferences–>General–>Connection–>Data Connection", change to PORT, that is, active mode, and start uploading. For a document of about 300MB, the speed can be guaranteed to be between 55~60KB/S, which is still ideal. In FlashFxp, you can also set it to active mode, as shown in the figure. In the site manager, for the corresponding site, remove the option in front of the passive mode.
FlashFxp settings image:

Use passive mode, speed picture

Passive mode, the upload speed is very fast at the beginning, but it becomes very slow immediately
Upload speed after FTP changed to active mode:

site5 FTP active mode upload speed is very fast