Forum Discussion
With the fastL4 profile assigned LTM shouldn't be doing anything at the application level, especially something that would limit the authentication methods available for ssh. Without knowing more here are some things I'd initially check:
1) Is your server configured to only allow public key authentication? If so, is your putty instance configured to send this public key when connecting to the VIP (as opposed to directly to the server)?
2) Are you sure the session is going to the server an not some other system? Verify with tcpdump on the BIGIP or 'show sys connection' when you perform a test to make sure the session is going to the server.
3) Perhaps a configuration on the server limiting authentication methods based on source IP? The LTM is configured to SNAT client connections (automap). Verify on the server or test from the BIGIP by attempting an ssh connection to the server. Assuming no odd routing config it should source from the self-IP in the same network as the floating self-IP for automap, but just verify this when you test.