diff --git a/doc/classes/@GlobalScope.xml b/doc/classes/@GlobalScope.xml
index 193c0e8a2..acb974c8e 100644
--- a/doc/classes/@GlobalScope.xml
+++ b/doc/classes/@GlobalScope.xml
@@ -102,6 +102,8 @@
 		<member name="ResourceSaver" type="ResourceSaver" setter="" getter="">
 			The [ResourceSaver] singleton.
 		</member>
+		<member name="SceneSynchronizerDebugger" type="Node" setter="" getter="">
+		</member>
 		<member name="ScriptServer" type="ScriptServer" setter="" getter="">
 			The [ScriptServer] singleton.
 		</member>
diff --git a/doc/classes/ProjectSettings.xml b/doc/classes/ProjectSettings.xml
index 5c79e6c4c..1b98378ae 100644
--- a/doc/classes/ProjectSettings.xml
+++ b/doc/classes/ProjectSettings.xml
@@ -172,6 +172,14 @@
 		</member>
 		<member name="NetworkSynchronizer/debug_server_speedup" type="bool" setter="" getter="" default="false">
 		</member>
+		<member name="NetworkSynchronizer/debugger/dump_classes" type="Array" setter="" getter="" default="[  ]">
+		</member>
+		<member name="NetworkSynchronizer/debugger/dump_enabled" type="bool" setter="" getter="" default="false">
+		</member>
+		<member name="NetworkSynchronizer/debugger/log_debug_fps_warnings" type="bool" setter="" getter="" default="true">
+		</member>
+		<member name="NetworkSynchronizer/log_debug_warnings_and_messages" type="bool" setter="" getter="" default="true">
+		</member>
 		<member name="android/modules" type="String" setter="" getter="" default="&quot;&quot;">
 			Comma-separated list of custom Android modules (which must have been built in the Android export templates) using their Java package path, e.g. [code]"org/godotengine/godot/MyCustomSingleton,com/example/foo/FrenchFriesFactory"[/code].
 			[b]Note:[/b] Since Godot 3.2.2, the [code]org/godotengine/godot/GodotPaymentV3[/code] module was deprecated and replaced by the [code]GodotPayment[/code] plugin which should be enabled in the Android export preset under [code]Plugins[/code] section. The singleton to access in code was also renamed to [code]GodotPayment[/code].
diff --git a/modules/network_synchronizer/doc_classes/DataBuffer.xml b/modules/network_synchronizer/doc_classes/DataBuffer.xml
index ba8ac4c53..d20006829 100644
--- a/modules/network_synchronizer/doc_classes/DataBuffer.xml
+++ b/modules/network_synchronizer/doc_classes/DataBuffer.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="DataBuffer" inherits="Object" version="3.5" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../doc/class.xsd">
+<class name="DataBuffer" inherits="Object" version="4.2">
 	<brief_description>
 	</brief_description>
 	<description>
diff --git a/modules/network_synchronizer/doc_classes/InputNetworkEncoder.xml b/modules/network_synchronizer/doc_classes/InputNetworkEncoder.xml
new file mode 100644
index 000000000..11bf2c376
--- /dev/null
+++ b/modules/network_synchronizer/doc_classes/InputNetworkEncoder.xml
@@ -0,0 +1,60 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="InputNetworkEncoder" inherits="Resource" version="4.2">
+	<brief_description>
+	</brief_description>
+	<description>
+	</description>
+	<tutorials>
+	</tutorials>
+	<methods>
+		<method name="are_different" qualifiers="const">
+			<return type="bool" />
+			<argument index="0" name="buffer_a" type="Object" />
+			<argument index="1" name="buffer_b" type="Object" />
+			<description>
+			</description>
+		</method>
+		<method name="count_size" qualifiers="const">
+			<return type="int" />
+			<argument index="0" name="buffer" type="Object" />
+			<description>
+			</description>
+		</method>
+		<method name="decode" qualifiers="const">
+			<return type="Array" />
+			<argument index="0" name="buffer" type="Object" />
+			<description>
+			</description>
+		</method>
+		<method name="encode" qualifiers="const">
+			<return type="void" />
+			<argument index="0" name="inputs" type="Array" />
+			<argument index="1" name="buffer" type="Object" />
+			<description>
+			</description>
+		</method>
+		<method name="find_input_id" qualifiers="const">
+			<return type="int" />
+			<argument index="0" name="name" type="StringName" />
+			<description>
+			</description>
+		</method>
+		<method name="get_defaults" qualifiers="const">
+			<return type="Array" />
+			<description>
+			</description>
+		</method>
+		<method name="register_input">
+			<return type="int" />
+			<argument index="0" name="name" type="StringName" />
+			<argument index="1" name="default_value" type="Variant" />
+			<argument index="2" name="type" type="int" enum="DataBuffer.DataType" />
+			<argument index="3" name="compression_level" type="int" enum="DataBuffer.CompressionLevel" />
+			<argument index="4" name="comparison_floating_point_precision" type="float" default="1e-05" />
+			<description>
+			</description>
+		</method>
+	</methods>
+	<constants>
+	</constants>
+</class>
diff --git a/modules/network_synchronizer/doc_classes/NetworkedController.xml b/modules/network_synchronizer/doc_classes/NetworkedController.xml
index 5e5b27693..2cc86117b 100644
--- a/modules/network_synchronizer/doc_classes/NetworkedController.xml
+++ b/modules/network_synchronizer/doc_classes/NetworkedController.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="NetworkedController" inherits="Node" version="3.5" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../doc/class.xsd">
+<class name="NetworkedController" inherits="Node" version="4.2">
 	<brief_description>
 	</brief_description>
 	<description>
@@ -81,7 +81,6 @@
 		</method>
 		<method name="player_get_pretended_delta" qualifiers="const">
 			<return type="float" />
-			<argument index="0" name="iterations_per_seconds" type="int" />
 			<description>
 			</description>
 		</method>
@@ -115,24 +114,30 @@
 		</member>
 		<member name="input_storage_size" type="int" setter="set_player_input_storage_size" getter="get_player_input_storage_size" default="180">
 		</member>
-		<member name="max_frames_delay" type="int" setter="set_max_frames_delay" getter="get_max_frames_delay" default="6">
+		<member name="max_frames_delay" type="int" setter="set_max_frames_delay" getter="get_max_frames_delay" default="7">
 		</member>
-		<member name="max_redundant_inputs" type="int" setter="set_max_redundant_inputs" getter="get_max_redundant_inputs" default="5">
+		<member name="max_redundant_inputs" type="int" setter="set_max_redundant_inputs" getter="get_max_redundant_inputs" default="6">
 		</member>
-		<member name="min_frames_delay" type="int" setter="set_min_frames_delay" getter="get_min_frames_delay" default="1">
-		</member>
-		<member name="net_sensitivity" type="float" setter="set_net_sensitivity" getter="get_net_sensitivity" default="0.1">
+		<member name="min_frames_delay" type="int" setter="set_min_frames_delay" getter="get_min_frames_delay" default="0">
 		</member>
 		<member name="network_traced_frames" type="int" setter="set_network_traced_frames" getter="get_network_traced_frames" default="120">
 		</member>
 		<member name="server_controlled" type="bool" setter="set_server_controlled" getter="get_server_controlled" default="false">
 		</member>
-		<member name="tick_acceleration" type="float" setter="set_tick_acceleration" getter="get_tick_acceleration" default="2.0">
+		<member name="tick_acceleration" type="float" setter="set_tick_acceleration" getter="get_tick_acceleration" default="5.0">
 		</member>
-		<member name="tick_speedup_notification_delay" type="float" setter="set_tick_speedup_notification_delay" getter="get_tick_speedup_notification_delay" default="0.33">
+		<member name="tick_speedup_notification_delay" type="int" setter="set_tick_speedup_notification_delay" getter="get_tick_speedup_notification_delay" default="600">
 		</member>
 	</members>
 	<signals>
+		<signal name="client_speedup_adjusted">
+			<argument index="0" name="input_worst_receival_time_ms" type="int" />
+			<argument index="1" name="optimal_frame_delay" type="int" />
+			<argument index="2" name="current_frame_delay" type="int" />
+			<argument index="3" name="distance_to_optimal" type="int" />
+			<description>
+			</description>
+		</signal>
 		<signal name="controller_reset">
 			<description>
 			</description>
@@ -145,6 +150,11 @@
 			<description>
 			</description>
 		</signal>
+		<signal name="input_missed">
+			<argument index="0" name="missing_input_id" type="int" />
+			<description>
+			</description>
+		</signal>
 	</signals>
 	<constants>
 	</constants>
diff --git a/modules/network_synchronizer/doc_classes/SceneDiff.xml b/modules/network_synchronizer/doc_classes/SceneDiff.xml
new file mode 100644
index 000000000..4cac80dbd
--- /dev/null
+++ b/modules/network_synchronizer/doc_classes/SceneDiff.xml
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="SceneDiff" inherits="Object" version="4.2">
+	<brief_description>
+	</brief_description>
+	<description>
+	</description>
+	<tutorials>
+	</tutorials>
+	<methods>
+	</methods>
+	<constants>
+	</constants>
+</class>
diff --git a/modules/network_synchronizer/doc_classes/SceneSynchronizer.xml b/modules/network_synchronizer/doc_classes/SceneSynchronizer.xml
index 8d9d68446..964e59e83 100644
--- a/modules/network_synchronizer/doc_classes/SceneSynchronizer.xml
+++ b/modules/network_synchronizer/doc_classes/SceneSynchronizer.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="SceneSynchronizer" inherits="Node" version="3.5" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../doc/class.xsd">
+<class name="SceneSynchronizer" inherits="Node" version="4.2">
 	<brief_description>
 		The `SceneSynchronizer` is used to synchronize all the peers using server authoritative networking model.
 	</brief_description>
@@ -49,7 +49,7 @@
 		<method name="find_action_id" qualifiers="const">
 			<return type="int" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="event_name" type="String" />
+			<argument index="1" name="event_name" type="StringName" />
 			<description>
 			</description>
 		</method>
@@ -79,7 +79,7 @@
 		<method name="get_variable_id">
 			<return type="int" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="variable" type="String" />
+			<argument index="1" name="variable" type="StringName" />
 			<description>
 			</description>
 		</method>
@@ -133,11 +133,11 @@
 		<method name="register_action">
 			<return type="int" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="action_func" type="String" />
-			<argument index="2" name="action_encoding_func" type="String" />
+			<argument index="1" name="action_func" type="StringName" />
+			<argument index="2" name="action_encoding_func" type="StringName" />
 			<argument index="3" name="can_client_trigger" type="bool" default="false" />
 			<argument index="4" name="wait_server_validation" type="bool" default="false" />
-			<argument index="5" name="server_action_validation_func" type="String" default="&quot;&quot;" />
+			<argument index="5" name="server_action_validation_func" type="StringName" default="@&quot;&quot;" />
 			<description>
 				Register an new action.
 				`node` The node that owns the event
@@ -157,15 +157,15 @@
 		<method name="register_process">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="function" type="String" />
+			<argument index="1" name="function" type="StringName" />
 			<description>
 			</description>
 		</method>
 		<method name="register_variable">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="variable" type="String" />
-			<argument index="2" name="on_change_notify" type="String" default="&quot;&quot;" />
+			<argument index="1" name="variable" type="StringName" />
+			<argument index="2" name="on_change_notify" type="StringName" default="@&quot;&quot;" />
 			<argument index="3" name="flags" type="int" enum="NetEventFlag" default="17" />
 			<description>
 			</description>
@@ -198,7 +198,7 @@
 		<method name="set_skip_rewinding">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="variable" type="String" />
+			<argument index="1" name="variable" type="StringName" />
 			<argument index="2" name="skip_rewinding" type="bool" />
 			<description>
 			</description>
@@ -230,9 +230,9 @@
 		<method name="track_variable_changes">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="variable" type="String" />
+			<argument index="1" name="variable" type="StringName" />
 			<argument index="2" name="object" type="Object" />
-			<argument index="3" name="method" type="String" />
+			<argument index="3" name="method" type="StringName" />
 			<argument index="4" name="flags" type="int" enum="NetEventFlag" default="17" />
 			<description>
 			</description>
@@ -252,7 +252,7 @@
 		<method name="trigger_action_by_name">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="event_name" type="String" />
+			<argument index="1" name="event_name" type="StringName" />
 			<argument index="2" name="arguments" type="Array" default="[  ]" />
 			<argument index="3" name="recipients_peers" type="PoolIntArray" default="PoolIntArray(  )" />
 			<description>
@@ -270,23 +270,23 @@
 		<method name="unregister_process">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="function" type="String" />
+			<argument index="1" name="function" type="StringName" />
 			<description>
 			</description>
 		</method>
 		<method name="unregister_variable">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="variable" type="String" />
+			<argument index="1" name="variable" type="StringName" />
 			<description>
 			</description>
 		</method>
 		<method name="untrack_variable_changes">
 			<return type="void" />
 			<argument index="0" name="node" type="Node" />
-			<argument index="1" name="variable" type="String" />
+			<argument index="1" name="variable" type="StringName" />
 			<argument index="2" name="object" type="Object" />
-			<argument index="3" name="method" type="String" />
+			<argument index="3" name="method" type="StringName" />
 			<description>
 			</description>
 		</method>
@@ -302,6 +302,15 @@
 		</member>
 	</members>
 	<signals>
+		<signal name="desync_detected">
+			<argument index="0" name="input_id" type="int" />
+			<argument index="1" name="node" type="Object" />
+			<argument index="2" name="var_names" type="Array" />
+			<argument index="3" name="client_values" type="Array" />
+			<argument index="4" name="server_values" type="Array" />
+			<description>
+			</description>
+		</signal>
 		<signal name="sync_paused">
 			<description>
 			</description>
diff --git a/modules/network_synchronizer/doc_classes/SceneSynchronizerDebugger.xml b/modules/network_synchronizer/doc_classes/SceneSynchronizerDebugger.xml
new file mode 100644
index 000000000..c3045734c
--- /dev/null
+++ b/modules/network_synchronizer/doc_classes/SceneSynchronizerDebugger.xml
@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<class name="SceneSynchronizerDebugger" inherits="Node" version="4.2">
+	<brief_description>
+	</brief_description>
+	<description>
+	</description>
+	<tutorials>
+	</tutorials>
+	<methods>
+		<method name="add_node_message">
+			<return type="void" />
+			<argument index="0" name="node" type="Node" />
+			<argument index="1" name="message" type="String" />
+			<description>
+			</description>
+		</method>
+		<method name="add_node_message_by_path">
+			<return type="void" />
+			<argument index="0" name="node_path" type="String" />
+			<argument index="1" name="message" type="String" />
+			<description>
+			</description>
+		</method>
+		<method name="debug_error">
+			<return type="void" />
+			<argument index="0" name="node" type="Node" />
+			<argument index="1" name="message" type="String" />
+			<argument index="2" name="silent" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="debug_print">
+			<return type="void" />
+			<argument index="0" name="node" type="Node" />
+			<argument index="1" name="message" type="String" />
+			<argument index="2" name="silent" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="debug_warning">
+			<return type="void" />
+			<argument index="0" name="node" type="Node" />
+			<argument index="1" name="message" type="String" />
+			<argument index="2" name="silent" type="bool" />
+			<description>
+			</description>
+		</method>
+		<method name="on_node_added">
+			<return type="void" />
+			<argument index="0" name="arg0" type="Node" />
+			<description>
+			</description>
+		</method>
+		<method name="on_node_removed">
+			<return type="void" />
+			<argument index="0" name="arg0" type="Node" />
+			<description>
+			</description>
+		</method>
+	</methods>
+	<constants>
+	</constants>
+</class>