If you are experiencing issues with finding your ARK PS4 server, make sure that the Session Filter drop-down value is set to "Unofficial PC Sessions". If you have a password on your server, make sure the Show Password Protected box is checked. You can find both of these at the bottom left portion of the server browser menu.
If you are running a Primitive Plus server, make sure that you choose the game mode at the bottom right of the main ARK menu. You will be prompted to confirm a change in game mode.
Do so and the game will reload. You will be able to find yo