diff --git a/telethon/network/connection/tcpabridged.py b/telethon/network/connection/tcpabridged.py
index cff295ae..c9350da9 100644
--- a/telethon/network/connection/tcpabridged.py
+++ b/telethon/network/connection/tcpabridged.py
@@ -11,7 +11,8 @@ class ConnectionTcpAbridged(Connection):
     """
     async def connect(self, timeout=None, ssl=None):
         await super().connect(timeout=timeout, ssl=ssl)
-        await self.send(b'\xef')
+        self._writer.write(b'\xef')
+        await self._writer.drain()
 
     def _write(self, data):
         """
diff --git a/telethon/network/connection/tcpintermediate.py b/telethon/network/connection/tcpintermediate.py
index 322b1e8f..59467be7 100644
--- a/telethon/network/connection/tcpintermediate.py
+++ b/telethon/network/connection/tcpintermediate.py
@@ -10,7 +10,8 @@ class ConnectionTcpIntermediate(Connection):
     """
     async def connect(self, timeout=None, ssl=None):
         await super().connect(timeout=timeout, ssl=ssl)
-        await self.send(b'\xee\xee\xee\xee')
+        self._writer.write(b'\xee\xee\xee\xee')
+        await self._writer.drain()
 
     def _send(self, data):
         self._writer.write(struct.pack('<i', len(data)) + data)
diff --git a/telethon/network/connection/tcpobfuscated.py b/telethon/network/connection/tcpobfuscated.py
index 5f2ca7e4..bfd4945c 100644
--- a/telethon/network/connection/tcpobfuscated.py
+++ b/telethon/network/connection/tcpobfuscated.py
@@ -1,6 +1,5 @@
 import os
 
-from .connection import Connection
 from .tcpabridged import ConnectionTcpAbridged
 from ...crypto import AESModeCTR
 
@@ -48,4 +47,5 @@ class ConnectionTcpObfuscated(ConnectionTcpAbridged):
         self._aes_decrypt = AESModeCTR(decrypt_key, decrypt_iv)
 
         random[56:64] = self._aes_encrypt.encrypt(bytes(random))[56:64]
-        await self._send(random)
+        self._writer.write(random)
+        await self._writer.drain()