Profinet Error (PNIO0042): Fast startup for Profinet submodule ... cannot be configured as long as the master does not support fast startup.
The Fast Start Up (FSU) function of a Profinet module can only be used if the Profinet controller added to your project supports this function. Whether your Profinet controller supports FSU can be seen in the 'Settings' editor of the 'Profinet' PLANT node. If supported, the editor provides the 'Fast StartUp' category with activated 'DCP hello supported' checkbox (checkbox is read-only).
For further information refer to the topic "Configuring Fast Start Up (FSU) for Profinet I/O"