Unity Networking Code not working

Hello Everyone I have a small code I am writing and when I try to get it in multiplayer it gives me an unreachable code error. I am new to networking with unity so i don't know that much about scripting with it.

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine.Networking;
 
 public class ConsoleGUI : NetworkBehaviour {
     public float Xsize = 1f;
     public float Ysize = 2f;
     public float Xposition = 1f;
     public float Yposition = 2f;
 
     public float Xsize1 = 1f;
     public float Ysize1 = 2f;
     public float Xposition1 = 1f;
     public float Yposition1 = 2f;
 
     public List<string> List = new List<string> ();
 
     public string String;
     public string InputString = "";
     // Use this for initialization
     void Start () {
         String = "Console Started Established Link";
     }
     
     // Update is called once per frame
     void Update () {
         if (isLocalPlayer){
             return;
             if (Input.GetKeyDown (KeyCode.Return)) {
                 if (InputString == "ls") {
                     String = String + "\n(Directories)" + "\n" + List [0] + "\n" + List [1] + "\n" + List [2] + "\n" + List [3];
                     InputString = "";
                 }
 
 
 
                 if (InputString == "cd " + List [1]) {
                     String = String + "\n(Changed directory to desktop)";
                     InputString = "";
                 }
                 if (InputString == "cd " + List [0]) {
                     String = String + "\n(Changed directory to root)";
                     InputString = "";
                 }
                 if (InputString == "cd " + List [2]) {
                     String = String + "\n(Changed directory to system)";
                     InputString = "";
                 }
                 if (InputString == "cd " + List [3]) {
                     String = String + "\n(Can not open " + List [3] + ")";
                     InputString = "";
                 }
 
 
             }
 
 
 
         }
     }
     void OnGUI()
     {
         if (isLocalPlayer) {
             GUI.Box (new Rect (Xposition, Yposition, Xsize, Ysize), String);
             GUI.skin.box.wordWrap = true;
             InputString = GUI.TextField (new Rect (Xposition1, Yposition1, Xsize1, Ysize1), InputString, 25);
         }
     }
 }