Relating to this question about
sftping files between Android and OSX, I'd like to know under what conditions an SFTP server responds with
500 SSH-2.0-<client program> not understood.
On the OSX command line, I type
sftp -oport=<port> <user>@<ip>
but on the Android side I get
500 SSH-2.0-OPENSSH_7.4 not understood
What configurations do I need to make in order to connect to an SFTP server running on Android?