diff --git a/Build/MQTTnet.nuspec b/Build/MQTTnet.nuspec
index 88dc7027..7dc215f1 100644
--- a/Build/MQTTnet.nuspec
+++ b/Build/MQTTnet.nuspec
@@ -13,12 +13,16 @@
     <releaseNotes> * [Core] Performance optimizations.
 * [Core] Due to performance reasons the timestamp of log messages is now in UTC format.
 * [Core] Added several packet validations.
+* [Core] Log messages now contain the complete source path including parent components.
+* [Core] The adapter now has an _Endpoint_ definition as string containing remote IP and port.
 * [Client] Received messages are now processed in the worker thread by default. Added a new setting for switching back to dedicated threads.
 * [ManagedClient] Fixed a loading issue of stored application messages (thanks to @JTrotta).
 * [Server] Added support for other WebSocket sub protocol formats like mqttv-3.1.1 (thanks to @israellot).
 * [Server] The takeover of an existing client sessions is now treated as a _clean_ disconnect of the previous client.
 * [Server] The pending messages queue per client is now limited to 250 messages. Overflow strategy and count can be changed via options (thanks to @VladimirAkopyan)
 * [Server] Keep alive checking is now suspended while large packages are being received (and thus the client is connected). Keep alive checking continues after a large packet is received completely.
+* [Server] Rewritten the _ConnectedClients_ API and added new features for disconnecting and Endpoint information (IP etc.).
+* [Server] Added settings for disabling persistent sessions and defining a max pending messages queue size per session.
     </releaseNotes>
     <copyright>Copyright Christian Kratky 2016-2018</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> 
diff --git a/Extensions/MQTTnet.Extensions.Rpc/MqttRpcClient.cs b/Extensions/MQTTnet.Extensions.Rpc/MqttRpcClient.cs
index e8242791..717f74ea 100644
--- a/Extensions/MQTTnet.Extensions.Rpc/MqttRpcClient.cs
+++ b/Extensions/MQTTnet.Extensions.Rpc/MqttRpcClient.cs
@@ -9,7 +9,7 @@ using MQTTnet.Protocol;
 
 namespace MQTTnet.Extensions.Rpc
 {
-    public sealed class MqttRpcClient : IDisposable
+    public class MqttRpcClient : IDisposable
     {
         private readonly ConcurrentDictionary<string, TaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, TaskCompletionSource<byte[]>>();
         private readonly IMqttClient _mqttClient;
diff --git a/Frameworks/MQTTnet.NetStandard/Adapter/MqttChannelAdapter.cs b/Frameworks/MQTTnet.NetStandard/Adapter/MqttChannelAdapter.cs
index 157e7653..7b8f08a9 100644
--- a/Frameworks/MQTTnet.NetStandard/Adapter/MqttChannelAdapter.cs
+++ b/Frameworks/MQTTnet.NetStandard/Adapter/MqttChannelAdapter.cs
@@ -13,7 +13,7 @@ using MQTTnet.Serializer;
 
 namespace MQTTnet.Adapter
 {
-    public sealed class MqttChannelAdapter : IMqttChannelAdapter
+    public class MqttChannelAdapter : IMqttChannelAdapter
     {
         private const uint ErrorOperationAborted = 0x800703E3;
         private const int ReadBufferSize = 4096;  // TODO: Move buffer size to config
diff --git a/Frameworks/MQTTnet.NetStandard/Adapter/ReceivedMqttPacket.cs b/Frameworks/MQTTnet.NetStandard/Adapter/ReceivedMqttPacket.cs
index c6768f99..1f1c59a9 100644
--- a/Frameworks/MQTTnet.NetStandard/Adapter/ReceivedMqttPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Adapter/ReceivedMqttPacket.cs
@@ -3,7 +3,7 @@ using System.IO;
 
 namespace MQTTnet.Adapter
 {
-    public sealed class ReceivedMqttPacket : IDisposable
+    public class ReceivedMqttPacket : IDisposable
     {
         public ReceivedMqttPacket(byte fixedHeader, MemoryStream body)
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetChildLogger.cs b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetChildLogger.cs
index 50557319..1ae5a9c3 100644
--- a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetChildLogger.cs
+++ b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetChildLogger.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Diagnostics
 {
-    public sealed class MqttNetChildLogger : IMqttNetChildLogger
+    public class MqttNetChildLogger : IMqttNetChildLogger
     {
         private readonly IMqttNetLogger _logger;
         private readonly string _source;
diff --git a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessage.cs b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessage.cs
index 6035a89c..107d8f34 100644
--- a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessage.cs
+++ b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessage.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Diagnostics
 {
-    public sealed class MqttNetLogMessage
+    public class MqttNetLogMessage
     {
         public MqttNetLogMessage(string logId, DateTime timestamp, int threadId, string source, MqttNetLogLevel level, string message, Exception exception)
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessagePublishedEventArgs.cs b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessagePublishedEventArgs.cs
index 2407752b..8a0c0fcb 100644
--- a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessagePublishedEventArgs.cs
+++ b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogMessagePublishedEventArgs.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Diagnostics
 {
-    public sealed class MqttNetLogMessagePublishedEventArgs : EventArgs
+    public class MqttNetLogMessagePublishedEventArgs : EventArgs
     {
         public MqttNetLogMessagePublishedEventArgs(MqttNetLogMessage logMessage)
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogger.cs b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogger.cs
index 6afeba19..56a664e4 100644
--- a/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogger.cs
+++ b/Frameworks/MQTTnet.NetStandard/Diagnostics/MqttNetLogger.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Diagnostics
 {
-    public sealed class MqttNetLogger : IMqttNetLogger
+    public class MqttNetLogger : IMqttNetLogger
     {
         private readonly string _logId;
 
diff --git a/Frameworks/MQTTnet.NetStandard/Exceptions/MqttCommunicationTimedOutException.cs b/Frameworks/MQTTnet.NetStandard/Exceptions/MqttCommunicationTimedOutException.cs
index 86f58b38..df3c4255 100644
--- a/Frameworks/MQTTnet.NetStandard/Exceptions/MqttCommunicationTimedOutException.cs
+++ b/Frameworks/MQTTnet.NetStandard/Exceptions/MqttCommunicationTimedOutException.cs
@@ -2,10 +2,14 @@
 
 namespace MQTTnet.Exceptions
 {
-    public sealed class MqttCommunicationTimedOutException : MqttCommunicationException
+    public class MqttCommunicationTimedOutException : MqttCommunicationException
     {
-        public MqttCommunicationTimedOutException() { }
-        public MqttCommunicationTimedOutException(Exception innerException) : base(innerException) { }
+        public MqttCommunicationTimedOutException()
+        {
+        }
 
+        public MqttCommunicationTimedOutException(Exception innerException) : base(innerException)
+        {
+        }
     }
 }
diff --git a/Frameworks/MQTTnet.NetStandard/Exceptions/MqttProtocolViolationException.cs b/Frameworks/MQTTnet.NetStandard/Exceptions/MqttProtocolViolationException.cs
index 8756b3f8..262f4afb 100644
--- a/Frameworks/MQTTnet.NetStandard/Exceptions/MqttProtocolViolationException.cs
+++ b/Frameworks/MQTTnet.NetStandard/Exceptions/MqttProtocolViolationException.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Exceptions
 {
-    public sealed class MqttProtocolViolationException : Exception
+    public class MqttProtocolViolationException : Exception
     {
         public MqttProtocolViolationException(string message)
             : base(message)
diff --git a/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.Uwp.cs b/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.Uwp.cs
index 15f8566e..a325ebe1 100644
--- a/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.Uwp.cs
+++ b/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.Uwp.cs
@@ -14,7 +14,7 @@ using MQTTnet.Client;
 
 namespace MQTTnet.Implementations
 {
-    public sealed class MqttTcpChannel : IMqttChannel
+    public class MqttTcpChannel : IMqttChannel
     {
         // ReSharper disable once MemberCanBePrivate.Global
         // ReSharper disable once AutoPropertyCanBeMadeGetOnly.Global
diff --git a/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs b/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs
index 40edf367..ab2675a8 100644
--- a/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs
+++ b/Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs
@@ -13,7 +13,7 @@ using MQTTnet.Client;
 
 namespace MQTTnet.Implementations
 {
-    public sealed class MqttTcpChannel : IMqttChannel
+    public class MqttTcpChannel : IMqttChannel
     {
         private readonly MqttClientTcpOptions _options;
 
diff --git a/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs b/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs
index 733bcdd1..3243cd76 100644
--- a/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs
+++ b/Frameworks/MQTTnet.NetStandard/Implementations/MqttWebSocketChannel.cs
@@ -8,7 +8,7 @@ using MQTTnet.Client;
 
 namespace MQTTnet.Implementations
 {
-    public sealed class MqttWebSocketChannel : IMqttChannel
+    public class MqttWebSocketChannel : IMqttChannel
     {
         private readonly SemaphoreSlim _sendLock = new SemaphoreSlim(1, 1);
         private readonly MqttClientWebSocketOptions _options;
diff --git a/Frameworks/MQTTnet.NetStandard/Internal/AsyncLock.cs b/Frameworks/MQTTnet.NetStandard/Internal/AsyncLock.cs
index 1de1b1a9..87878fa9 100644
--- a/Frameworks/MQTTnet.NetStandard/Internal/AsyncLock.cs
+++ b/Frameworks/MQTTnet.NetStandard/Internal/AsyncLock.cs
@@ -5,7 +5,7 @@ using System.Threading.Tasks;
 namespace MQTTnet.Internal
 {
     // From Stephen Toub (https://blogs.msdn.microsoft.com/pfxteam/2012/02/12/building-async-coordination-primitives-part-6-asynclock/)
-    public sealed class AsyncLock : IDisposable
+    public class AsyncLock : IDisposable
     {
         private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1, 1);
         private readonly Task<IDisposable> _releaser;
@@ -30,7 +30,7 @@ namespace MQTTnet.Internal
             _semaphore?.Dispose();
         }
 
-        private sealed class Releaser : IDisposable
+        private class Releaser : IDisposable
         {
             private readonly AsyncLock _toRelease;
 
diff --git a/Frameworks/MQTTnet.NetStandard/MqttApplicationMessage.cs b/Frameworks/MQTTnet.NetStandard/MqttApplicationMessage.cs
index 387acb21..334dfb40 100644
--- a/Frameworks/MQTTnet.NetStandard/MqttApplicationMessage.cs
+++ b/Frameworks/MQTTnet.NetStandard/MqttApplicationMessage.cs
@@ -1,23 +1,9 @@
-using System;
-using MQTTnet.Protocol;
+using MQTTnet.Protocol;
 
 namespace MQTTnet
 {
-    public sealed class MqttApplicationMessage
+    public class MqttApplicationMessage
     {
-        public MqttApplicationMessage()
-        {
-        }
-
-        [Obsolete("Use object initializer or _MqttApplicationMessageBuilder_ instead.")]
-        public MqttApplicationMessage(string topic, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, bool retain)
-        {
-            Topic = topic ?? throw new ArgumentNullException(nameof(topic));
-            Payload = payload ?? throw new ArgumentNullException(nameof(payload));
-            QualityOfServiceLevel = qualityOfServiceLevel;
-            Retain = retain;
-        }
-
         public string Topic { get; set; }
 
         public byte[] Payload { get; set; }
diff --git a/Frameworks/MQTTnet.NetStandard/MqttApplicationMessageReceivedEventArgs.cs b/Frameworks/MQTTnet.NetStandard/MqttApplicationMessageReceivedEventArgs.cs
index a16a81d1..e81c69a9 100644
--- a/Frameworks/MQTTnet.NetStandard/MqttApplicationMessageReceivedEventArgs.cs
+++ b/Frameworks/MQTTnet.NetStandard/MqttApplicationMessageReceivedEventArgs.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet
 {
-    public sealed class MqttApplicationMessageReceivedEventArgs : EventArgs
+    public class MqttApplicationMessageReceivedEventArgs : EventArgs
     {
         public MqttApplicationMessageReceivedEventArgs(string clientId, MqttApplicationMessage applicationMessage)
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttConnAckPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttConnAckPacket.cs
index 9cf0adfe..dbdeea89 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttConnAckPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttConnAckPacket.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Packets
 {
-    public sealed class MqttConnAckPacket : MqttBasePacket
+    public class MqttConnAckPacket : MqttBasePacket
     {
         public bool IsSessionPresent { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttConnectPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttConnectPacket.cs
index b1943ced..2134f4bb 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttConnectPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttConnectPacket.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Packets
 {
-    public sealed class MqttConnectPacket : MqttBasePacket
+    public class MqttConnectPacket : MqttBasePacket
     {
         public MqttProtocolVersion ProtocolVersion { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttDisconnectPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttDisconnectPacket.cs
index 46c3270d..621829a2 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttDisconnectPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttDisconnectPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttDisconnectPacket : MqttBasePacket
+    public class MqttDisconnectPacket : MqttBasePacket
     {
         public override string ToString()
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttPingReqPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttPingReqPacket.cs
index fee9926c..5c65da1d 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttPingReqPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttPingReqPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttPingReqPacket : MqttBasePacket
+    public class MqttPingReqPacket : MqttBasePacket
     {
         public override string ToString()
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttPingRespPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttPingRespPacket.cs
index c5f82a3b..b6f9bc3c 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttPingRespPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttPingRespPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttPingRespPacket : MqttBasePacket
+    public class MqttPingRespPacket : MqttBasePacket
     {
         public override string ToString()
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubAckPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubAckPacket.cs
index e7fe57b7..3015f278 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubAckPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubAckPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttPubAckPacket : MqttBasePublishPacket
+    public class MqttPubAckPacket : MqttBasePublishPacket
     {
         public override string ToString()
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubCompPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubCompPacket.cs
index 98dace70..e9ea18eb 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubCompPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubCompPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttPubCompPacket : MqttBasePublishPacket
+    public class MqttPubCompPacket : MqttBasePublishPacket
     {
         public override string ToString()
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRecPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRecPacket.cs
index 86cd4b45..0184d6b8 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRecPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRecPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttPubRecPacket : MqttBasePublishPacket
+    public class MqttPubRecPacket : MqttBasePublishPacket
     {
         public override string ToString()
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRelPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRelPacket.cs
index ed1d933b..bb37655c 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRelPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttPubRelPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttPubRelPacket : MqttBasePublishPacket
+    public class MqttPubRelPacket : MqttBasePublishPacket
     {
         public override string ToString()
         {
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttPublishPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttPublishPacket.cs
index 52fcceed..55144a9e 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttPublishPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttPublishPacket.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Packets
 {
-    public sealed class MqttPublishPacket : MqttBasePublishPacket
+    public class MqttPublishPacket : MqttBasePublishPacket
     {
         public bool Retain { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttSubAckPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttSubAckPacket.cs
index 3b8cf7a8..05e18b2b 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttSubAckPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttSubAckPacket.cs
@@ -4,7 +4,7 @@ using MQTTnet.Protocol;
 
 namespace MQTTnet.Packets
 {
-    public sealed class MqttSubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
+    public class MqttSubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort? PacketIdentifier { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttSubscribePacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttSubscribePacket.cs
index 63aede16..60086c47 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttSubscribePacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttSubscribePacket.cs
@@ -3,7 +3,7 @@ using System.Linq;
 
 namespace MQTTnet.Packets
 {
-    public sealed class MqttSubscribePacket : MqttBasePacket, IMqttPacketWithIdentifier
+    public class MqttSubscribePacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort? PacketIdentifier { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubAckPacket.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubAckPacket.cs
index 688195fa..ab5f9f62 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubAckPacket.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubAckPacket.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Packets
 {
-    public sealed class MqttUnsubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
+    public class MqttUnsubAckPacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort? PacketIdentifier { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubscribe.cs b/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubscribe.cs
index a4d84535..63895f12 100644
--- a/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubscribe.cs
+++ b/Frameworks/MQTTnet.NetStandard/Packets/MqttUnsubscribe.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Packets
 {
-    public sealed class MqttUnsubscribePacket : MqttBasePacket, IMqttPacketWithIdentifier
+    public class MqttUnsubscribePacket : MqttBasePacket, IMqttPacketWithIdentifier
     {
         public ushort? PacketIdentifier { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Serializer/ByteReader.cs b/Frameworks/MQTTnet.NetStandard/Serializer/ByteReader.cs
index ec1e3ea2..461bba33 100644
--- a/Frameworks/MQTTnet.NetStandard/Serializer/ByteReader.cs
+++ b/Frameworks/MQTTnet.NetStandard/Serializer/ByteReader.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Serializer
 {
-    public sealed class ByteReader
+    public class ByteReader
     {
         private readonly int _source;
         private int _index;
diff --git a/Frameworks/MQTTnet.NetStandard/Serializer/ByteWriter.cs b/Frameworks/MQTTnet.NetStandard/Serializer/ByteWriter.cs
index af961e1a..9ae21564 100644
--- a/Frameworks/MQTTnet.NetStandard/Serializer/ByteWriter.cs
+++ b/Frameworks/MQTTnet.NetStandard/Serializer/ByteWriter.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Serializer
 {
-    public sealed class ByteWriter
+    public class ByteWriter
     {
         private int _index;
         private int _byte;
diff --git a/Frameworks/MQTTnet.NetStandard/Serializer/MqttPacketSerializer.cs b/Frameworks/MQTTnet.NetStandard/Serializer/MqttPacketSerializer.cs
index 369bd16a..8c384e07 100644
--- a/Frameworks/MQTTnet.NetStandard/Serializer/MqttPacketSerializer.cs
+++ b/Frameworks/MQTTnet.NetStandard/Serializer/MqttPacketSerializer.cs
@@ -8,7 +8,7 @@ using MQTTnet.Adapter;
 
 namespace MQTTnet.Serializer
 {
-    public sealed class MqttPacketSerializer : IMqttPacketSerializer
+    public class MqttPacketSerializer : IMqttPacketSerializer
     {
         public MqttProtocolVersion ProtocolVersion { get; set; } = MqttProtocolVersion.V311;
 
diff --git a/Frameworks/MQTTnet.NetStandard/Server/GetOrCreateClientSessionResult.cs b/Frameworks/MQTTnet.NetStandard/Server/GetOrCreateClientSessionResult.cs
index 8f5f085e..975d237f 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/GetOrCreateClientSessionResult.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/GetOrCreateClientSessionResult.cs
@@ -1,6 +1,6 @@
 namespace MQTTnet.Server
 {
-    public sealed class GetOrCreateClientSessionResult
+    public class GetOrCreateClientSessionResult
     {
         public bool IsExistingSession { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttClientKeepAliveMonitor.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttClientKeepAliveMonitor.cs
index 82bcbdf6..a4130889 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttClientKeepAliveMonitor.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttClientKeepAliveMonitor.cs
@@ -7,7 +7,7 @@ using MQTTnet.Packets;
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttClientKeepAliveMonitor
+    public class MqttClientKeepAliveMonitor
     {
         private readonly Stopwatch _lastPacketReceivedTracker = new Stopwatch();
         private readonly Stopwatch _lastNonKeepAlivePacketReceivedTracker = new Stopwatch();
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttClientPendingMessagesQueue.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttClientPendingMessagesQueue.cs
index 6227e020..97f616c0 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttClientPendingMessagesQueue.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttClientPendingMessagesQueue.cs
@@ -11,7 +11,7 @@ using MQTTnet.Protocol;
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttClientPendingMessagesQueue : IDisposable
+    public class MqttClientPendingMessagesQueue : IDisposable
     {
         private readonly AsyncAutoResetEvent _queueAutoResetEvent = new AsyncAutoResetEvent();
         private readonly IMqttServerOptions _options;
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSession.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSession.cs
index 6e537e9e..0f115534 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSession.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSession.cs
@@ -12,7 +12,7 @@ using MQTTnet.Protocol;
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttClientSession : IDisposable
+    public class MqttClientSession : IDisposable
     {
         private readonly MqttPacketIdentifierProvider _packetIdentifierProvider = new MqttPacketIdentifierProvider();
 
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs
index b9ab0136..7918aa8d 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSessionsManager.cs
@@ -12,7 +12,7 @@ using MQTTnet.Protocol;
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttClientSessionsManager : IDisposable
+    public class MqttClientSessionsManager : IDisposable
     {
         private readonly ConcurrentDictionary<string, MqttClientSession> _sessions = new ConcurrentDictionary<string, MqttClientSession>();
         private readonly AsyncLock _sessionPreparationLock = new AsyncLock();
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSubscriptionsManager.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSubscriptionsManager.cs
index 6dfa98e3..5f067ff6 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttClientSubscriptionsManager.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttClientSubscriptionsManager.cs
@@ -7,7 +7,7 @@ using MQTTnet.Protocol;
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttClientSubscriptionsManager
+    public class MqttClientSubscriptionsManager
     {
         private readonly ConcurrentDictionary<string, MqttQualityOfServiceLevel> _subscriptions = new ConcurrentDictionary<string, MqttQualityOfServiceLevel>();
         private readonly IMqttServerOptions _options;
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttRetainedMessagesManager.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttRetainedMessagesManager.cs
index 3ab53cbf..9fe454cf 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttRetainedMessagesManager.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttRetainedMessagesManager.cs
@@ -7,7 +7,7 @@ using MQTTnet.Diagnostics;
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttRetainedMessagesManager
+    public class MqttRetainedMessagesManager
     {
         private readonly ConcurrentDictionary<string, MqttApplicationMessage> _messages = new ConcurrentDictionary<string, MqttApplicationMessage>();
         private readonly IMqttNetChildLogger _logger;
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttServerDefaultEndpointOptions.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttServerDefaultEndpointOptions.cs
index 545499b5..0965104b 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttServerDefaultEndpointOptions.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttServerDefaultEndpointOptions.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttServerDefaultEndpointOptions
+    public class MqttServerDefaultEndpointOptions
     {
         public bool IsEnabled { get; set; } = true;
 
diff --git a/Frameworks/MQTTnet.NetStandard/Server/MqttServerTlsEndpointOptions.cs b/Frameworks/MQTTnet.NetStandard/Server/MqttServerTlsEndpointOptions.cs
index 73be93c5..aaf4948b 100644
--- a/Frameworks/MQTTnet.NetStandard/Server/MqttServerTlsEndpointOptions.cs
+++ b/Frameworks/MQTTnet.NetStandard/Server/MqttServerTlsEndpointOptions.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet.Server
 {
-    public sealed class MqttServerTlsEndpointOptions
+    public class MqttServerTlsEndpointOptions
     {
         public bool IsEnabled { get; set; }
 
diff --git a/Frameworks/MQTTnet.NetStandard/TopicFilter.cs b/Frameworks/MQTTnet.NetStandard/TopicFilter.cs
index 1dad73d0..7eebbc2c 100644
--- a/Frameworks/MQTTnet.NetStandard/TopicFilter.cs
+++ b/Frameworks/MQTTnet.NetStandard/TopicFilter.cs
@@ -2,7 +2,7 @@
 
 namespace MQTTnet
 {
-    public sealed class TopicFilter
+    public class TopicFilter
     {
         public TopicFilter(string topic, MqttQualityOfServiceLevel qualityOfServiceLevel)
         {