OnServerEvent and FireAllClient not communicating

In this instance, as @idkhowtousername said, just use Bindable events rather than a remote event. Remote events are only used when you want the Client to contact the Server, or the Server to contact the Client.

For Server → Server communication, or Client → Client, use Bindable events.

Bindable events documentation. - ROBLOX .
How do Bindable events work? - DevForum