SSH connection timeouts, duplicity does not respect --timeout option

[Olivier - interfaSys]

Our backup server seems to now take a long time to go through the authentication process or something is wrong with duplicity.

In order to determine if the long process is the problem, I've tried to raise the timeout limit, but duplicity doesn't seem to respect that.

The backend used is scp (scp://hostname), but sftp doesn't work either.
The options I use include:
 --timeout=160 --ssh-options='-oConnectTimeout=160'

I even edited globals.py to see if it would change something. It didn't.

The error message, using the wrapper duply, is:
--- Start running command STATUS at 16:16:04.000 ---
BackendException: ssh connection to hostname:22 failed: [Errno 64] Host is down
16:16:19.000 Task 'STATUS' failed with exit code '23'.
--- Finished state FAILED 'code 23' at 16:16:19.000 - Runtime 00:00:15.000 ---

It says the runtime is 15 seconds, which is way shorter than the timeout.

Connecting to the server directly via scp or sftp works.