diff --git a/Build/MQTTnet.AspNetCore.nuspec b/Build/MQTTnet.AspNetCore.nuspec
index b29ad5c..b98eec0 100644
--- a/Build/MQTTnet.AspNetCore.nuspec
+++ b/Build/MQTTnet.AspNetCore.nuspec
@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>MQTTnet.AspNetCore</id>
-    <version>2.5.2</version>
+    <version>2.5.3</version>
     <authors>Christian Kratky</authors>
     <owners>Christian Kratky</owners>
     <licenseUrl>https://github.com/chkr1011/MQTTnet/blob/master/LICENSE</licenseUrl>
@@ -10,14 +10,13 @@
     <iconUrl>https://raw.githubusercontent.com/chkr1011/MQTTnet/master/Images/Logo_128x128.png</iconUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>This is a support library to integrate MQTTnet into AspNetCore.</description>
-    <releaseNotes>* Updated to MQTTnet 2.5.2.
-* Fixed WebSocket protocol negotiation.
+    <releaseNotes>* Updated to MQTTnet 2.5.3.
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2017</copyright>
     <tags>MQTT Message Queue Telemetry Transport MQTTClient MQTTServer Server MQTTBroker Broker NETStandard IoT InternetOfThings Messaging Hardware Arduino Sensor Actuator M2M ESP Smart Home Cities Automation Xamarin</tags> 
     <dependencies>
       <group targetFramework="netstandard2.0">
-        <dependency id="MQTTnet" version="2.5.2" />
+        <dependency id="MQTTnet" version="2.5.3-rc1" />
       </group>
     </dependencies>
   </metadata>
diff --git a/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs b/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs
index 9046bb9..d8e24a4 100644
--- a/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs
+++ b/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs
@@ -31,7 +31,7 @@ namespace MQTTnet.Implementations
             var uri = _options.Uri;
             if (!uri.StartsWith("ws://", StringComparison.OrdinalIgnoreCase) && !uri.StartsWith("wss://", StringComparison.OrdinalIgnoreCase))
             {
-                if (!_options.TlsOptions.UseTls)
+                if (_options.TlsOptions?.UseTls == false)
                 {
                     uri = "ws://" + uri;
                 }
diff --git a/MQTTnet.Core/Server/MqttClientSubscriptionsManager.cs b/MQTTnet.Core/Server/MqttClientSubscriptionsManager.cs
index 8801c01..8d88ddc 100644
--- a/MQTTnet.Core/Server/MqttClientSubscriptionsManager.cs
+++ b/MQTTnet.Core/Server/MqttClientSubscriptionsManager.cs
@@ -27,7 +27,7 @@ namespace MQTTnet.Core.Server
                 foreach (var topicFilter in subscribePacket.TopicFilters)
                 {
                     var interceptorContext = new MqttSubscriptionInterceptorContext(clientId, topicFilter);
-                    _options.SubscriptionsInterceptor?.Invoke(interceptorContext);
+                    _options.SubscriptionInterceptor?.Invoke(interceptorContext);
                     responsePacket.SubscribeReturnCodes.Add(interceptorContext.AcceptSubscription ? MqttSubscribeReturnCode.SuccessMaximumQoS1 : MqttSubscribeReturnCode.Failure);
                     
                     if (interceptorContext.CloseConnection)
diff --git a/MQTTnet.Core/Server/MqttConnectionValidatorContext.cs b/MQTTnet.Core/Server/MqttConnectionValidatorContext.cs
new file mode 100644
index 0000000..83a1eab
--- /dev/null
+++ b/MQTTnet.Core/Server/MqttConnectionValidatorContext.cs
@@ -0,0 +1,25 @@
+using MQTTnet.Core.Protocol;
+
+namespace MQTTnet.Core.Server
+{
+    public class MqttConnectionValidatorContext
+    {
+        public MqttConnectionValidatorContext(string clientId, string username, string password, MqttApplicationMessage willMessage)
+        {
+            ClientId = clientId;
+            Username = username;
+            Password = password;
+            WillMessage = willMessage;
+        }
+
+        public string ClientId { get; }
+
+        public string Username { get; }
+
+        public string Password { get; }
+
+        public MqttApplicationMessage WillMessage { get; }
+
+        public MqttConnectReturnCode ReturnCode { get; set; } = MqttConnectReturnCode.ConnectionAccepted;
+    }
+}
diff --git a/MQTTnet.Core/Server/MqttServerOptions.cs b/MQTTnet.Core/Server/MqttServerOptions.cs
index 4b09676..8988b11 100644
--- a/MQTTnet.Core/Server/MqttServerOptions.cs
+++ b/MQTTnet.Core/Server/MqttServerOptions.cs
@@ -11,14 +11,14 @@ namespace MQTTnet.Core.Server
         public MqttServerTlsEndpointOptions TlsEndpointOptions { get; } = new MqttServerTlsEndpointOptions();
 
         public int ConnectionBacklog { get; set; } = 10;
-
+        
         public TimeSpan DefaultCommunicationTimeout { get; set; } = TimeSpan.FromSeconds(15);
 
         public Func<MqttConnectPacket, MqttConnectReturnCode> ConnectionValidator { get; set; }
 
         public Action<MqttApplicationMessageInterceptorContext> ApplicationMessageInterceptor { get; set; }
 
-        public Action<MqttSubscriptionInterceptorContext> SubscriptionsInterceptor { get; set; }
+        public Action<MqttSubscriptionInterceptorContext> SubscriptionInterceptor { get; set; }
 
         public IMqttServerStorage Storage { get; set; }
     }
diff --git a/MQTTnet.Core/Server/MqttServerOptionsBuilder.cs b/MQTTnet.Core/Server/MqttServerOptionsBuilder.cs
new file mode 100644
index 0000000..692f7c1
--- /dev/null
+++ b/MQTTnet.Core/Server/MqttServerOptionsBuilder.cs
@@ -0,0 +1,88 @@
+using System;
+using MQTTnet.Core.Packets;
+using MQTTnet.Core.Protocol;
+
+namespace MQTTnet.Core.Server
+{
+    public class MqttServerOptionsBuilder
+    {
+        private readonly MqttServerOptions _options = new MqttServerOptions();
+
+        public MqttServerOptionsBuilder WithConnectionBacklog(int value)
+        {
+            _options.ConnectionBacklog = value;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithDefaultCommunicationTimeout(TimeSpan value)
+        {
+            _options.DefaultCommunicationTimeout = value;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithDefaultEndpointPort(int value)
+        {
+            _options.DefaultEndpointOptions.Port = value;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithDefaultEndpoint()
+        {
+            _options.DefaultEndpointOptions.IsEnabled = true;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithoutDefaultEndpoint()
+        {
+            _options.DefaultEndpointOptions.IsEnabled = false;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithEncryptedEndpoint()
+        {
+            _options.TlsEndpointOptions.IsEnabled = true;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithoutEncryptedEndpoint()
+        {
+            _options.TlsEndpointOptions.IsEnabled = false;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithEncryptionCertificate(byte[] value)
+        {
+            _options.TlsEndpointOptions.Certificate = value;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithStorage(IMqttServerStorage value)
+        {
+            _options.Storage = value;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithConnectionValidator(Func<MqttConnectPacket, MqttConnectReturnCode> value)
+        {
+            _options.ConnectionValidator = value;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithApplicationMessageInterceptor(Action<MqttApplicationMessageInterceptorContext> value)
+        {
+            _options.ApplicationMessageInterceptor = value;
+            return this;
+        }
+
+        public MqttServerOptionsBuilder WithSubscriptionInterceptor(Action<MqttSubscriptionInterceptorContext> value)
+        {
+            _options.SubscriptionInterceptor = value;
+            return this;
+        }
+
+        public MqttServerOptions Build()
+        {
+            return _options;
+        }
+    }
+}
diff --git a/Tests/MQTTnet.TestApp.AspNetCore2/MQTTnet.TestApp.AspNetCore2.csproj b/Tests/MQTTnet.TestApp.AspNetCore2/MQTTnet.TestApp.AspNetCore2.csproj
index 7e4e0e3..553b341 100644
--- a/Tests/MQTTnet.TestApp.AspNetCore2/MQTTnet.TestApp.AspNetCore2.csproj
+++ b/Tests/MQTTnet.TestApp.AspNetCore2/MQTTnet.TestApp.AspNetCore2.csproj
@@ -10,7 +10,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.0" />
+    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.3" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/Tests/MQTTnet.TestApp.NetCore/ServerTest.cs b/Tests/MQTTnet.TestApp.NetCore/ServerTest.cs
index a0b1626..2a8180b 100644
--- a/Tests/MQTTnet.TestApp.NetCore/ServerTest.cs
+++ b/Tests/MQTTnet.TestApp.NetCore/ServerTest.cs
@@ -40,7 +40,7 @@ namespace MQTTnet.TestApp.NetCore
                             context.ApplicationMessage.Payload = Encoding.UTF8.GetBytes(DateTime.Now.ToString("O"));
                         }
                     },
-                    SubscriptionsInterceptor = context =>
+                    SubscriptionInterceptor = context =>
                     {
                         if (context.TopicFilter.Topic.StartsWith("admin/foo/bar") && context.ClientId != "theAdmin")
                         {