File size increased after copy from FTP

[mjlkr]

I've got ftp configured on FreeNAS 11.3-U3.2 and strange problem. When I copy files larger than 200MB, their size increase and they become broken (except one exe file which works, all of them are archives 7zip/zip). I've tried 3 ftp clients: Filezilla, WinSCP, Unreal Commander, always in binary mode. I realized that it happens only when I've got poor internet - can it be the reason?