FTP in transparent mode (data streaming) fails with Cinterion ELS61-E | Telit Cinterion IoT Developer Community

Good morning,

I can upload files to an ftp server by using non-transparent mode but not in transparent mode. After sending the data stream to the module ELS61 I send the escape sequence "+++" and the module answers "OK". However, after a while it informs that timeout is reached and then transfer is aborted.
Do I need to do something else after sending +++ in order to finish the transfer?

I enclose below the log of the commands to and answers from the modem.

Thanks for the attention.

*****LOG*****

at^siso=0

OK

^SIS: 0,0,2100,"Ftp open(agisco.cloud:4100)"

^SIS: 0,0,2100,"220-FileZilla Server 0.9.60 beta Welcome to Agisco FTP Service"

^SIS: 0,0,2100,"FTP Login OK"

^SIS: 0,0,2100,"put lolita.txt"

^SISW: 0,1

at^sist=0

CONNECT

Hello_world+++

OK

^SIS: 0,0,48,"Remote peer has closed the connection"

^SISR: 0,2

^SIS: 0,0,2100,"426 Connection timed out, aborting transfer of \22/test_guille/lolita.txt\22"

...and for completeness, here follows the service profile definition

at^siss?

^SISS:0,"srvType","Ftp"

^SISS:0,"conId","0"

^SISS:0,"address","ftp://my.server.url:21/test_guille"

^SISS:0,"tcpMR","10"

^SISS:0,"tcpOT","6000"

^SISS:0,"user","userid"

^SISS:0,"passwd","*****"

^SISS:0,"path",""

^SISS:0,"files","lolita.txt"

^SISS:0,"cmd","put"

^SISS:0,"ftMode","bin"

^SISS:1,"srvType",""

^SISS:2,"srvType",""

^SISS:3,"srvType",""

^SISS:4,"srvType",""

^SISS:5,"srvType",""

^SISS:6,"srvType",""

^SISS:7,"srvType",""

^SISS:8,"srvType",""

^SISS:9,"srvType",""

OK