Just a photograph of the two RN2483 modules and how they are connected.
From the code I cannot make up why it doesn't work, perhaps the phyical setup is wrong.
Otherwise I don't know it. I was able to communicate between my RN2483 module and a SX1276 module, so it should be possible to send and receive p2p.
Are you able to communicate with a gateway? Perhaps you can use the other module to eavesdrop on this connection.