Okay, I got this working. One of my network guys told me there was nothing special set up on the one server, but the admin corrected him and figured out only the one server had appropriate NATing to the remote. Love when stuff like this isn't documented... :P

Thanks. Now if I can get my other connections to work, I'll be golden. If not, I'll start a new thread.

Yes, that is a separate problem, and I don't need to pursue if I can't resolve the first issue. If and when I can, I will start a separate thread.

I just tried using the GUI on the server and it connected. Tried the GUI on my local client and it timed out (so I didn't retry the app). Let me see if I can get the app to the same server that works with the GUI and get a result.

Desaxman13 wrote:

Yes. Exactly the same result. The GUI does run on one server and the .Net app on a different server (long story...).

So the logs are from different machines? Can you reproduce the problem, when running GUI and .NET on the same machine?

I also tried code for a different SFTP connection (again using the code generated by the GUI) and it fails as well, this time for:
...

That looks like a completely different problem. If your want to pursue that, start a separate thread for it.

Yes. Exactly the same result. The GUI does run on one server and the .Net app on a different server (long story...). I also tried code for a different SFTP connection (again using the code generated by the GUI) and it fails as well, this time for:
"! 2018-01-24 17:03:41.940 Using username "TSOI40R".
. 2018-01-24 17:03:41.988 Server offered these authentication methods: password,keyboard-interactive
. 2018-01-24 17:03:41.989 Attempting keyboard-interactive authentication
. 2018-01-24 17:03:42.026 Prompt (keyboard interactive, "SSH server authentication", "Using keyboard-interactive authentication.", "Enter password: ")
. 2018-01-24 17:03:42.027 Using stored password.
! 2018-01-24 17:03:42.080 Further authentication required
. 2018-01-24 17:03:42.081 Further authentication required
. 2018-01-24 17:03:42.081 Server offered these authentication methods: password,keyboard-interactive
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. 2018-01-24 17:03:42.082 Attempting keyboard-interactive authentication
. 2018-01-24 17:03:42.123 Prompt (keyboard interactive, "SSH server authentication", "Using keyboard-interactive authentication.", "Enter password: ")
. 2018-01-24 17:03:42.123 Disconnected: Unable to authenticate"

I did run the GUI connection on this one locally as well as the .Net app locally to see if it changed things, but the GUI connects with no problem/additional authentication needed and the .Net assembly fails. At least on this session, it does actually start the connection.

Do you get the same problem, if you run your .NET code using the same local account that use you for WinSCP GUI (i.e. MMRI\administrator)?

I used the WinSCP client to generate the .Net assembly code, but while I can connect in the client, the .Net Assembly times out every time. Any help?