Is it possible to make 2 or devices communicate to each others directly - without using an internet connection ? In my case I need this to work outdoor with no internet connection - could one device “create and run” a local server and all devices connect to this server using the Network class ? If yes, how could I create un run a server using unity3D ?
Yes, if they’re on the same LAN. Then one device needs to host, and the other can connect to it by IP address.
If they’re not on any LAN then you would have to set up an ad hoc wifi connection between them, which is not trivial for users to do. There are other mechanisms supported for local device-to-device communication but I don’t think you’d be able to get the Network class to work with them.