When using the CA API Gateway as FTP proxy then it is possible that external FTP Client Software fail to connect the FTP Server via the Route via FTP(S) Assertion.
Example of the returned message:
>>> CWD /
<<< 257 "/"
Error EElFTPSUnacceptedReplyError: Unaccepted server reply (error code is 257)
These FTP Clients sending a CWD command to the Server which returns a error code 257.
The error code 257 is wrong and let the connection fail as "Unaccepted server reply".
Use a different FTP Client Software. Most FTP Clients do not show this problem.
The CA API Development Team did build a solution for Release 9.1 that can be requested from Support.
Please open a new Case with the CA Support Team.