What's wrong with FTP?

Question

System administration

I work under MacOS X 10.7.5, ForkLift 2.5.4, FireFTP clients.
Internet provider DomRU.
Recently, such a topic appeared - I rewrite two dozen jpg pictures that I created from my own photos.
Some pictures are about 30Kb, some are about 300Kb. Some of the files are overwritten, some are not.
I tried three hostings, sweb, valuehost, masterhost, the picture is the same everywhere:
- a 28.5Kb file is famously overwritten to 28.5Kb, after which the speed drops sharply,
- we wait a minute and the server gives an error, and on each hosting the errors are different.
- as a result, we have a file in a folder with a size of ZeroKb. We delete.
- large files are copied normally, you can see the picture on the server.
Here's what the servers are saying:
- 426 Failure reading network stream (masterhost)
- Copy error. Failed connect to server. (sweb, valuehost)
* * *
This situation arose unexpectedly, yesterday. Before that, I always worked with FTP without problems.
As a result, I copied the files to a USB flash drive, rewrote it at work (the same Mac) - everything is OK.
The question is - who to sin on in this situation, who to contact?
And why is it selectively buggy, not on all files?

Answer 1

Try to put the passive mode and fill in no more than 2-3 streams.
PS better as a ZIP archive via the web and unzip via the control panel (if possible).

Answer 2

The paranoid version - the provider turned on DPI (analysis of the contents of network packets) and somehow does not like your files :-)
I would look at the ftp session on the server using tcpdump.
By the way. If you upload files in one stream, the problem is reproduced?

Answer 3

Try an OpenVPN connection (through some VPN service), so everything will go by the provider. Find out if it has any effect.

Answer 4

More recently, there was something similar in questions, where everything went through an encrypted (HTTPS / SSH / SFTP) channel, and an unknown force acted on certain files through the usual one, which prevented the file from being transferred to the server. If possible, try the encrypted channel too.

Answer 5

And if the pictures from the server are deleted and uploaded again? At the same time, pay attention to the owner / group under which the files were originally uploaded to the server.