My problem is that my FTP work great, except when I upload files on a particular client server!

On this server it happens that some files are uploaded fine and others not. They stop halfway through the upload, then this error is displayed:

530 Sorry, the maximum number of clients (4) from your host are already connected. Unable to make a connection. Please try again.

Obviously this is not true, I'm the only one that is uploading!

Anyone had the same experience with this? I have tried many different FTP clients; they all display the same error or just hang up.


2 Answers 2


It's possible for a single ftp client to open multiple connections to a server, even though it looks like one to you, there might be multiple connections between your host and the server.

In a program like filezilla you can select File -> Site Manager On the Transfer Settings tab, set the Limit number of simultaneous connections field to, in your case, less than 4.

  • 1
    this somehow doesn't seem to work (anymore) in FileZilla 3.13.1. I changed the setting but I'm still getting the exact same error.
    – RubenGeert
    Commented Aug 30, 2015 at 4:41
  • In CyberDuck, you can go to Preferences > Transfers > Transfer Files and set it to Open single connection Commented Jun 4, 2019 at 10:34

There are two other possible causes for this error:

  1. The FTP server is sitting behind a NAT and sees all incoming connections arriving from the same IP address. (Don't laugh - I've seen this many times!) Therefore...you just happened to be the fourth connection...

  2. Other people from YOUR network are accessing the same FTP server. Since you all may appear to be coming from the same IP address...

There are FTP servers that allow you to lift limits like this for particular user accounts, user groups, IP ranges, etc.

  • Thank you, We change the networking type from NAT to bridge mode, and It's working, now. :) Commented Aug 22, 2016 at 6:25

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