Network.proxyIP  

function Awake() {
    Network.proxyIP = "1.1.1.1";
    Network.proxyPort = 1111;
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Awake() {
        Network.proxyIP = "1.1.1.1";
        Network.proxyPort = 1111;
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Awake():
        Network.proxyIP = '1.1.1.1'
        Network.proxyPort = 1111