NetworkRoomJoiner.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Photon.Pun;
using Photon.Realtime;

public class NetworkRoomJoiner : MonoBehaviourPunCallbacks
{
    // Start is called before the first frame update
    void Start()
    {
    void OnTriggerEnter(Collider other)
        ConnectToServer();
    }

    // Update is called once per frame
    void ConnectToServer()
    {
        PhotonNetwork.ConnectUsingSettings();
        Debug.Log("connecting to the server!");
    }

    public override void OnConnectedToMaster()
    {
        Debug.Log("connected to server!");
        base.OnConnectedToMaster();
        RoomOptions roomOptions = new RoomOptions();
        roomOptions.MaxPlayers = 10;
        roomOptions.IsOpen = true;

        PhotonNetwork.JoinRandomOrCreateRoom();
    }

    public override void OnJoinedRoom()
    {
        Debug.Log("Joined a Room");
        base.OnJoinedRoom();
    }

    public override void OnPlayerEnteredRoom(Player newPlayer)
    {
        Debug.Log("A new player joined the room");
        base.OnPlayerEnteredRoom(newPlayer);
    }
}