By default an Edge Gateway does not have a default Profinet device name. This is in accordance to the latest PI Profinet specification.
To get a Profinet communication up and running with a Profinet controller a Profinet device name needs to be assigned to the gateway first.
Assigning is done using the DCP protocol over a Profinet controller engineering software usually.
Until a gateway doesn't have a named assigned it reports just its MAC address during a DCP scan.