On Linux, Win32_OperatingSystem isn't built into the core OMI server; it is usually provided by the provider. Check if the SCX package is installed: Ubuntu/Debian: dpkg -l | grep scx RHEL/CentOS: rpm -qa | grep scx
omicli namespace list root/cimv2
The user account lacks "Remote Enable" permissions for the Root\CIMV2 namespace or lacks DCOM execution rights. win32-operatingsystem result not found via omi