FTP - upload problem

I'm having problems when I try to upload files via ftp, it shows that the upload was timed out or the file goes empty.

Normally, I can see/delete/download the files, but not upload them.

I already used many clients such as Transmit, FileZilla, Cyberduck and none of them has worked.

Also I tried turning on/off those Passive Modes on Apple's and clients' preferences. I'm not considering that the problem regards to the host, because when a I asked someone to upload for me it worked and when I use my old PC it works as well.

My OS is 10.6.8 and I connect through ethernet, not airport wireless.

I'd be glad if someone can help me with it.

Thanks