I know this is an old thread, but @altlaw's steps helped me to resolve a similar issue.
Using the -d option with my perfstat command for verbose output allowed me to see the plink.exe command, same as @altlaw. I manually ran the plink command from the verbose output, which returned "The first key-exchange algorithm supported by the server is below the configured warning threshold. Connection Abandoned." I had to change my default PuTTY settings for Key exchange by going to Category>Connection>SSH>Kex, moved the target key algorithm above the "- warn below here-", and saved Default Settings under 'Saved Sessions.'
I re-ran the previous perfstat command and still got the "SSH to filer fails! Quitting!" message, but this time found Syslog events on the filer itself relating to permissions issues. I escalated the permissions of the user that I was using in my perfstat command and was able to execute the perfstat successfully. Thanks @altlaw.
I hope this information helps others.