Ramendra,
FTP Services of webMethods are as such very much reliable, unless the network connection you operate on is not stable.
A few questions for you:
Do you use a firewall between webMethods server and your ftp server? what are the settings on firewall?
Does your firewall restrict you to get an ftp data connection on certain ports?
As I understand, you do not have a login issue. It is always with put and get. It is very likely that it is at the firewall level.
Regards,
#webmethods-Protocol-and-Transport#Integration-Server-and-ESB#webMethods