glynn ftp port config not working?

[fragrans]

I configured the port to 6000 in _glynn.yml, but glynn always gave timeout error. And you can find the port is still 21 in the error message.

# optional
ftp_port: 6000                  # default 21

connect(2) for "spbot.fake.com.cn" port 21 (Errno::ETIMEDOUT)

D:\coding.net\spbot>glynn
Configuration file: D:/coding.net/spbot/_config.yml
Building site: D:/coding.net/spbot -> D:/coding.net/spbot/_site
Configuration file: D:/coding.net/spbot/_config.yml
Successfully generated site
Sending site over FTP (host: spbot.fake.com.cn, port: 6000, ftps: false)
Connected to server. Sending site
C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:243:in `initialize': A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. - connect(2) for "spbot.fake.com.cn" port 21 (Errno::ETIMEDOUT)
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:243:in `open'
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:243:in `block in open_socket'
        from C:/tools/ruby23/lib/ruby/2.3.0/timeout.rb:74:in `timeout'
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:238:in `open_socket'
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:263:in `block in connect'
        from C:/tools/ruby23/lib/ruby/2.3.0/monitor.rb:214:in `mon_synchronize'
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:262:in `connect'
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:175:in `initialize'
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:148:in `new'
        from C:/tools/ruby23/lib/ruby/2.3.0/net/ftp.rb:148:in `open'
        from C:/tools/ruby23/lib/ruby/gems/2.3.0/gems/glynn-1.2.3/lib/glynn/ftp.rb:23:in `connect'
        from C:/tools/ruby23/lib/ruby/gems/2.3.0/gems/glynn-1.2.3/lib/glynn/ftp.rb:16:in `sync'
        from C:/tools/ruby23/lib/ruby/gems/2.3.0/gems/glynn-1.2.3/bin/glynn:80:in `'
        from C:/tools/ruby23/bin/glynn:23:in `load'
        from C:/tools/ruby23/bin/glynn:23:in `'