Hi,
you don't need several pc to test, you simply publish your app, duplicate it as many time as you want and run them all.
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- PlayMaker event if not sent using Photon actions will only be received locally, in order for a PlayMaker event to go over the network, you need to send and RPC ( you'll find actions for this).
- Photon do not allow players to communicate if not in the same room, so no Player A in room X can not contact Player B in room Y.
However, you can do that using the Photon Chat sdk, you combine PUN and Chat sdk together and use Player authorization Id ( when they sign in your game, or as you define unity Id for player sessions), and then you can start having Players communicating across rooms. That's already pretty advanced, so some warning applies if you have no experience with medium complexity coding.
Bye,
Jean