For some reason, the site I connect to doesn't work well with the "Optimize connection buffer size" enabled, and whenever I had that on while downloading files larger than a few megabytes, I'd get this error: Server unexpectedly closed network connection.
Fortunately, I found how to turn it off and (in the GUI version at least) all my transfers are successful. On the contrary, in batch mode from a script file, even after setting
-rawsettings SendBuf=0 appended to the
open command, the connection will "unexpectedly close" on files larger than a few megabytes.
SendBuf=0 completely turn off the feature as the GUI checkbox does?