diff --git a/telethon/network/mtprotolayer.py b/telethon/network/mtprotolayer.py
index 2960b28e..d3cd7ae4 100644
--- a/telethon/network/mtprotolayer.py
+++ b/telethon/network/mtprotolayer.py
@@ -34,6 +34,9 @@ class MTProtoLayer:
         """
         self._connection.disconnect()
 
+    def reset_state(self):
+        self._state = MTProtoState(self._state.auth_key)
+
     async def send(self, state_list):
         """
         The list of `RequestState` that will be sent. They will
diff --git a/telethon/network/mtprotosender.py b/telethon/network/mtprotosender.py
index 8196932c..5dc5a530 100644
--- a/telethon/network/mtprotosender.py
+++ b/telethon/network/mtprotosender.py
@@ -8,7 +8,8 @@ from .mtprotoplainsender import MTProtoPlainSender
 from .requeststate import RequestState
 from .. import utils
 from ..errors import (
-    BadMessageError, SecurityError, TypeNotFoundError, rpc_message_to_error
+    BadMessageError, BrokenAuthKeyError, SecurityError, TypeNotFoundError,
+    rpc_message_to_error
 )
 from ..extensions import BinaryReader
 from ..helpers import _ReadyQueue
@@ -279,6 +280,9 @@ class MTProtoSender:
         """
         self._reconnecting = True
 
+        __log__.debug('Closing current connection...')
+        self._connection.disconnect()
+
         __log__.debug('Awaiting for the send loop before reconnecting...')
         await self._send_loop_handle
 
@@ -290,22 +294,24 @@ class MTProtoSender:
 
         self._reconnecting = False
 
+        # Start with a clean state (and thus session ID) to avoid old msgs
+        self._connection.reset_state()
+
         retries = self._retries if self._auto_reconnect else 0
         for retry in range(1, retries + 1):
             try:
                 await self._connect()
-                # TODO Keep this?
-                """
-                for m in self._pending_messages.values():
-                    self._send_queue.put_nowait(m)
-                """
+            except ConnectionError:
+                __log__.info('Failed reconnection retry %d/%d', retry, retries)
+            else:
+                self._send_queue.extend(self._pending_state.values())
+                self._pending_state.clear()
 
+                # TODO Where is this needed?
                 if self._auto_reconnect_callback:
                     self._loop.create_task(self._auto_reconnect_callback())
 
                 break
-            except ConnectionError:
-                __log__.info('Failed reconnection retry %d/%d', retry, retries)
         else:
             __log__.error('Failed to reconnect automatically.')
             await self._disconnect(error=ConnectionError())
@@ -356,11 +362,36 @@ class MTProtoSender:
         Besides `connect`, only this method ever receives data.
         """
         while self._user_connected and not self._reconnecting:
-            # TODO Handle timeout, cancelled, arbitrary, broken auth, buffer,
-            # security and type not found.
+            # TODO handle incomplete read?
             __log__.debug('Receiving items from the network...')
-            message = await self._connection.recv()
-            await self._process_message(message)
+            try:
+                message = await self._connection.recv()
+            except TypeNotFoundError as e:
+                __log__.info('Type %08x not found, remaining data %r',
+                             e.invalid_constructor_id, e.remaining)
+                continue
+            except SecurityError as e:
+                # A step while decoding had the incorrect data. This message
+                # should not be considered safe and it should be ignored.
+                __log__.warning('Security error while unpacking a '
+                                'received message: %s', e)
+                continue
+            except asyncio.CancelledError:
+                return
+            except (BrokenAuthKeyError, BufferError):
+                __log__.info('Broken authorization key; resetting')
+                self._connection._state.auth_key = None
+                self._start_reconnect()
+                return
+            except Exception:
+                __log__.exception('Unhandled error while receiving data')
+                self._start_reconnect()
+                return
+            else:
+                try:
+                    await self._process_message(message)
+                except Exception:
+                    __log__.exception('Unhandled error while processing msgs')
 
     # Response Handlers
 
diff --git a/telethon/network/mtprotostate.py b/telethon/network/mtprotostate.py
index e38dad60..4b3dbefa 100644
--- a/telethon/network/mtprotostate.py
+++ b/telethon/network/mtprotostate.py
@@ -120,6 +120,7 @@ class MTProtoState:
             else:
                 raise BufferError("Can't decode packet ({})".format(body))
 
+        # TODO Check salt, session_id and sequence_number
         key_id = struct.unpack('<Q', body[:8])[0]
         if key_id != self.auth_key.key_id:
             raise SecurityError('Server replied with an invalid auth key')