I have a WP7700 running firmware release 9.1, and a WP8548 running firmware release 16.
I have modified the curl recipe in both to include libssh2.
The WP8548 can connect to an SFTP server, but the WP7700 cannot.
The libs and versions running on each appear to be identical.
This problem is very easy to reproduce, simply add libssh2 to the curl recipe and recompile.
I would love to have a developer chime in on this issue, I have been battling with it for weeks and I have a 150 WP7700s that need to get out in the field.