Hello Chen,
Thanks for replying back and taking interest for resolving this issue. 
Just to give more info,we have all the role installed like HPDM Server,Gateway,Master repository controller on same server.
And I did some more testing from my test t510 are below ....
1) Login to t510 and open X-terminal
2) Connect to the FTP server and then to master repository
3) Downloading some files from master repository ... ( below is the whole log) - Successful
root@t510:/writable/home/user# ftp
ftp> open <IP address of HPDM FTP Server>
Connected to <IP address of HPDM FTP Server>.
220 Microsoft FTP Service
Name (IP address Of HPDM FTP Server:root): FTP UserName
331 Password required for "FTP UserName
Password:
230 User logged in.
Remote system type is Windows_NT.
ftp> cd HPDM/Repository/Tools/Imaging/HPThinPro5
250 CWD command successful.
ftp> ls
200 PORT command successful.
150 Opening ASCII mode data connection.
08-14-15 03:20PM 304 menu.lst
08-14-15 03:20PM 643 postpack.sh
08-14-15 03:20PM 1916 prepack.sh
08-14-15 03:20PM 409 S04repack
226 Transfer complete.
ftp> get menu.lst
local: menu.lst remote: menu.lst
200 PORT command successful.
150 Opening ASCII mode data connection.
WARNING! 13 bare linefeeds received in ASCII mode
File may not have transferred correctly.
226 Transfer complete.
304 bytes received in 0.01 secs (30.4 kB/s)
ftp> get prepack.sh
local: prepack.sh remote: prepack.sh
200 PORT command successful.
150 Opening ASCII mode data connection.
WARNING! 73 bare linefeeds received in ASCII mode
File may not have transferred correctly.
226 Transfer complete.
1916 bytes received in 0.00 secs (1982.1 kB/s)
ftp> bye
221 Goodbye.
root@t510:/writable/home/user# ls
Desktop menu.lst prepack.sh
root@t510:/writable/home/user# ls
Desktop menu.lst prepack.sh
4) Now connect to the same master repository from "Easy Update" tool with same user name and password ... It's failing
I wanted to understand when we tried from X-terminal then it is using port 21 for connect to FTP and able download the files
But when we are connecting via East Update tool which port it uses to browse the FTP path ?
Please help.