FTP Connection was reset

[picosan]

I'm trying to backup via FTP.
Whilst I'm able to initially connect, to pick a folder for example, i very quickly run into an error:
Recv failure: Connection was reset [curl_easy_perform]

The FTP provider told me:
"your FTP connection was blocked by the firewall by triggering the below rule:
GPL FTP RNFR overflow attempt
https://snort.org/rule_docs/1-3077
"
Is there anything to be done?
As a side note, via WinSCP I can connect on port 21 with explicit ssl (certificate shows TLS1.3 is used).
Via freefilesync I can only connect with encryption disabled.

[Zenju]

FTP is generally unsafe, as it sends all data in plain text

That's obviously not true when the connection is encrypted by setting "Explicit SSL/TLS". When you're able to pick a folder this means you've successfully connected to the server.

Perhaps "Snort" is simply blocking "RNFR"?

The RNFR command is issued when an FTP client wants to rename a file on the server

[picosan]

I was unable to connect with "Explicit SSL/TLS" (even though I can do so via WinSCP)?

[Zenju]

I was unable to connect with "Explicit SSL/TLS" (even though I can do so via WinSCP)?

Whilst I'm able to initially connect, to pick a folder

Now, what is it?

[picosan]

Now, what is it?

As per my first post: Via freefilesync I can only connect with encryption disabled.

[John1234]

Normally port 21 is reserved for unencrypted connections via traditional FTP. Perhaps you can ask the admin if there is a separate SFTP encrypted port number such as 22 for example. 22 is the longstanding default for encryption over SSH which gives you SFTP an encrypted FTP connection.

I use a higher port # to deter hackers.