proftp 계정 접속 문제 [공유기 사용]

현제 테스트 사용환경은 페도라 R3
팬4 1.6G/256m/가정용 라인  ProFTPD Version 1.2.10 입니다.

공유기 내에 설정으로 8668번 포트를 열어주어서 접속은 되는 상태이구요.
내부아이피로 ftp에 접속을 하면 잘되지만 외부에서 접속을하면

파일 리스트도 않보이고 업로드 및 다운로드 역시도 않되는 상황입니다.
proftpd.conf 설정은 아래와 같습니다.

ServerName                      ".: Welcome"
ServerType                      standalone
#ServerType                    inetd
DefaultServer                  on
ServerAdmin                    test@mail.mail
# Port 21 is the standard FTP port.
Port                            8668

# Umask 022 is a good standard umask to prevent new dirs and files
# from being group and world writable.
Umask                          022

# To prevent DoS attacks, set the maximum number of child processes
# to 30.  If you need to allow more than 30 concurrent connections
# at once, simply increase this value.  Note that this ONLY works
# in standalone mode, in inetd mode you should use an inetd server
# that allows you to limit maximum number of processes per service
# (such as xinetd).
MaxInstances                    10

# Set the user and group under which the server will run.
User                            nobody
Group                          nobody

# To cause every FTP user to be "jailed" (chrooted) into their home
# directory, uncomment this line.
DefaultRoot ~

# Normally, we want files to be overwriteable.
AllowOverwrite          on

# Bar use of SITE CHMOD by default
<Limit SITE_CHMOD>
  DenyAll
</Limit>
# We want 'welcome.msg' displayed at login, and '.message' displayed
# in each newly chdired directory.

  DisplayLogin          welcome.msg
  DisplayFirstChdir    .message

# A basic anonymous configuration, no upload directories.  If you do not
# want anonymous users, simply delete this entire <Anonymous> section.

#<Anonymous ~ftp>
#  User                        ftp
#  Group                                ftp
#
#  # We want clients to be able to login with "anonymous" as well as "ftp"
#  UserAlias                    anonymous ftp
#
#  # Limit the maximum number of anonymous logins
  MaxClients                    5 "sorry :-)"
  MaxClientsPerHost            1 "sorry :-)"
#
#  # Limit WRITE everywhere in the anonymous chroot
#  <Limit WRITE>
#    DenyAll
#  </Limit>
#</Anonymous>

보시고 리눅스 선배님들의 조언 부탁 드리겠습니다.
좋은하루 되세요 :-)