Cannot login my Freenas server

Iam trying to log in my freenas server user account over internet using SCP,without success. Sometimes the password is not authenticated,though it is correct and sometimes there is "Network error. Connection timed out",though the internet connection is ok.
How to proceed? It's very frustrating. The freenas is SSH AND FTP enabled and version of winscp is 4.2.9

Did You try Version 4.1.9?

Which Windows Version are You using? XP/Vista/7

I'm trying to log in my Free NAS server from my Windows XP Home laptop. Haven't tried version 4.1.9, will give it a try.

I can connect over home LAN using WinSCP 4.1.9 from windows XP Home laptop,but not over the internet using mobile broadband. Server is detected but authentication fails with the same password ,which was used successfully over home LAN.What to do now?