When one try to add F5 device do the SolarWinds (via Add Node) and Test iControl credentials (user&pass) then message for invalid password and too restricted access granted for the user on the device are the same.
Please update Test routine to return more detailed information, for example:
"Login failed. Check credentials."
"Credentials correct but we can't access X/Y/Z -- does the user have Administrator role?"
and maybe more for more possible exit statuses.
