How do I properly use Set Gravity Scale with replication?

I’m trying to set up a simple glider the player can deploy when in air to avoid falling damage. I can make the glider mesh appear fine but can’t seem to change the speed at which the player falls. I originally tried to do this client side, and realized I probably need an RPC, but I don’t seem to be able to implement it properly.

The blueprint script I’m using is attached. Any ideas?

I have some additional questions going through this created, which I haven’t been able to find answers to as well:

  1. Does something like this need to be reliable? What are reliable RPCs generally used for?
  2. Do variables passed through RPCs also need to be replicated?