v2rayN/ServiceLib/Models/V2rayConfig.cs

@@ -292,7 +292,7 @@ namespace ServiceLib.Models
 
         public object response { get; set; }
 
-        public string? domain { get; set; }
+        public string domain { get; set; }
     }
 
     public class KcpSettings4Ray

v2rayN/ServiceLib/Services/CoreConfig/CoreConfigV2rayService.cs

@@ -916,7 +916,7 @@ namespace ServiceLib.Services.CoreConfig
                         kcpSettings.header = new Header4Ray
                         {
                             type = node.HeaderType,
-                            domain = host.IsNullOrEmpty() ? null : host
+                            domain = host
                         };
                         if (Utils.IsNotEmpty(path))
                         {