Setting name and color on client is handled by server and updated to clients

Assets/Scripts/ColorManipulation.cs

@@ -0,0 +1,6 @@
+using UnityEngine;
+
+public static class ColorManipulation
+{
+    public static Color GetRandomColor() => new(Random.value, Random.value, Random.value);
+}

Assets/Scripts/ColorManipulation.cs.meta

@@ -1,5 +1,5 @@
 fileFormatVersion: 2
-guid: 200a2e870f62694458ff9e42c9fa7ff5
+guid: 5c5b7d3af1f171c46b09250081a08927
 MonoImporter:
   externalObjects: {}
   serializedVersion: 2

Assets/Scripts/MyNetworkManager.cs

@@ -9,8 +9,8 @@ public class MyNetworkManager : NetworkManager
 
         MyNetworkPlayer player = conn.identity.GetComponent<MyNetworkPlayer>();
         player.SetDisplayName($"Player {numPlayers.ToString()}");
-        player.SetPlayerColor(GetRandomColor());
+        player.SetPlayerColor(ColorManipulation.GetRandomColor());
     }
     
-    private static Color GetRandomColor() => new(Random.value, Random.value, Random.value);
+    
 }

Assets/Scripts/MyNetworkPlayer.cs

@@ -1,4 +1,3 @@
-using System;
 using Mirror;
 using TMPro;
 using UnityEngine;
@@ -7,6 +6,7 @@ public class MyNetworkPlayer : NetworkBehaviour
 {
     [Header("Connections")]
     [SerializeField] private TMP_Text _playerNameObject;
+
     [Header("Variables")]
     [SyncVar(hook = nameof(SetPlayerNameTagText))]
     [SerializeField]
@@ -16,6 +16,8 @@ public class MyNetworkPlayer : NetworkBehaviour
     [SerializeField]
     private Color _playerColor = Color.black;
 
+    #region Server
+
     [Server]
     public void SetDisplayName(string newDisplayName)
     {
@@ -28,6 +30,43 @@ public class MyNetworkPlayer : NetworkBehaviour
         _playerColor = newPlayerColor;
     }
 
+    [Command]
+    private void CmdSetDisplayName(string newDisplayName)
+    {
+        if (NameLengthIsCorrect(newDisplayName))
+        {
+            RpcDebugLog($"Setting player names{newDisplayName}");
+            SetDisplayName(newDisplayName);
+        }
+        else
+        {
+            RpcDebugLog($"new name: {newDisplayName} : is too long");
+        }
+    }
+
+    [Command]
+    private void CmdSetNewColor()
+    {
+        Color newColor = ColorManipulation.GetRandomColor();
+        RpcDebugLog($"Setting player color{newColor.ToString()}");
+        SetPlayerColor(newColor);
+    }
+
+    private bool NameLengthIsCorrect(string newDisplayName)
+    {
+        return newDisplayName.Length < 10;
+    }
+
+    [ClientRpc]
+    private void RpcDebugLog(string message)
+    {
+        Debug.Log(message);
+    }
+
+    #endregion
+
+    #region Client
+
     private void SetPlayerNameTagText(string oldText, string newText)
     {
         if (_playerNameObject != null)
@@ -43,4 +82,18 @@ public class MyNetworkPlayer : NetworkBehaviour
             _playerNameObject.color = newColor;
         }
     }
+
+    [ContextMenu("SetName")]
+    private void SetMyName()
+    {
+        CmdSetDisplayName("New Name");
+    }
+
+    [ContextMenu("NewColor")]
+    private void SetNewColor()
+    {
+        CmdSetNewColor();
+    }
+
+    #endregion
 }

Assets/Scripts/MyNetworkPlayer1.cs

@@ -1,11 +0,0 @@
-using Mirror;
-using UnityEngine;
-
-public class MyNetworkPlayer1 : NetworkBehaviour
-{
-    [SyncVar]
-    [SerializeField]
-    private Transform _transform;
-
-
-}