IIS enviromet

https://docs.appeon.com/2015/workarounds_and_api_guide/ch01s03s04.html#deploy_file_server_iis

the  of_logonfileserver returns and error when the application is acces out of the internal Network
the rest of the application is working with no problems but when try to connect to the fileserver from an external IP it returns and error
we check the fileserver log and there is no entry of the error 

in the internarl network it works 

 this is the code

ls_server = '10.0.8.252' //for external use we change it to sistemas.msa.com.py
ll_puerto = 807

if ls_import_file_name = '' then
Messagebox("file service", "Please select a file to upload.")
return
end if
ls_path_file = AppeonGetCacheDir()
lappeonfileservice = CREATE appeonfileservice
lap = create appeonextfuncs
IF ( IsValid( lappeonfileservice ) ) THEN
ll_retVal = lappeonfileservice.of_logonfileserver(ls_server,ll_puerto, "username=userA;password=userA" )
IF ( ll_retVal <> 0 ) THEN
MessageBox( 'File server error', 'Could not connect to file server !!!~r~nOperation aborted !', StopSign!, OK! )
ELSE