Might be your local connection speed or server - I load 700+ pages of 250K each in a few minutes consistantly........

Adrian

Hello. I sent a notification about your question to the company employees, expect an answer from them here in the comments.

If the internet connection is unstable, it can also lead to such problems.
Are there red error messages when uploading to ftp?
Have you ever tried to set the number of transferred files to 1?
(This can be increased again with stable internet access.)

JJ.

If too many errors are found in the upload within a time window on the server,
the upload is canceled by the server.
This can be the reason for canceling the upload.
Is there enough free space on the server?

JJ.