The plugin (check_ms_iis_application_pool.ps1 OEPool) requested does not exist. You may be trying to access the 'check_ms_iis_application_pool.ps1' node.
And post the result. I believe that solving this is a matter of sending the command (from linux) in a format where the command (on Windows) is correctly interpreting the "OEPool" argument.
UDI@<SRV>:[~]: /usr/local/nagios/libexec/check_ncpa.py -H <SRV NAME> -t '<Token>' -P 5693 -M 'plugins/check_ms_iis_application_pool.ps1 -A OEPool'
The plugin (check_ms_iis_application_pool.ps1 -A OEPool) requested does not exist. You may be trying to access the 'check_ms_iis_application_pool.ps1' node.
I can't find anything on the internet regarding using this plugin with ncpa. Everything I've been able to find deals with using the plugin with nrpe. It could be that when sent over ncpa, the argument syntax is malformed.
One thing that stands out is that the pool argument should be -a '-A <Name-Of-Application-Pool>' including the single quotes.
In view of the fact that there is no documentation regarding the check_ms_iis_application_pool with NCPA, it's quite possible that the configuration is not supported. As this is a third party plugin, we are unable to speak to this directly. If you've found an alternative that is addressing your needs, may we close this topic?