Ah ok.
You could ping it via Network Binding
https://docs.openhab.org/v2.2/addons/bindings/network/readme.html
Thing
Thing network:pingdevice:nas [ hostname=“192.168.0.42” ]
Item
Switch NAS “NAS ist [MAP(online.map):%s]” { channel=“network:pingdevice:nas:online” }
Perhaps with MAP Translation Service
online.map
ON=online
OFF=offline
And then shown as “dummy” widget in hapbanel