Last but not least we have one last problem of replication. This one is very important to use sporadically and only on simulating environment that MUST replicate on all the clients connected. If you check the simulation of the boxes on all clients you will see that sometimes they become unsynchronized. This happens because even when the projectiles are being replicated the simulations are running separately on each client. This different evaluations by different clients with different graphic loads will make impossible to generate the same responses on environment simulations.
But some game mechanics may need to update rigorous simulations on all clients, like for example if a simulated rock should crush a character or something.
Lets create a new blueprint throw in a cube from the content browser. The blueprint should look something like this but beware that you will need to find better ways of updating its position to the other players.
There you are, if you replace all the boxes with this blueprint actor everything inside the FPS Template will replicate on every player that connects to the server.
Have fun!