diff --git a/jupyter_server/services/kernels/connection/abc.py b/jupyter_server/services/kernels/connection/abc.py
index f918466c9..4bdf6e3ed 100644
--- a/jupyter_server/services/kernels/connection/abc.py
+++ b/jupyter_server/services/kernels/connection/abc.py
@@ -1,5 +1,5 @@
 from abc import ABC, abstractmethod
-from typing import Callable
+from typing import Any
 
 
 class KernelWebsocketConnectionABC(ABC):
@@ -10,7 +10,7 @@ class KernelWebsocketConnectionABC(ABC):
     interface.
     """
 
-    write_message: Callable
+    websocket_handler: Any
 
     @abstractmethod
     async def connect(self):
diff --git a/jupyter_server/services/kernels/connection/base.py b/jupyter_server/services/kernels/connection/base.py
index 12b062e78..fc8e1f8f0 100644
--- a/jupyter_server/services/kernels/connection/base.py
+++ b/jupyter_server/services/kernels/connection/base.py
@@ -3,7 +3,8 @@
 import sys
 
 from jupyter_client.session import Session
-from traitlets import Callable, Float, Instance, default
+from tornado.websocket import WebSocketHandler
+from traitlets import Float, Instance, default
 from traitlets.config import LoggingConfigurable
 
 try:
@@ -135,7 +136,7 @@ def _default_kernel_info_timeout(self):
     def _default_session(self):
         return Session(config=self.config)
 
-    write_message = Callable()
+    websocket_handler = Instance(WebSocketHandler)
 
     async def connect(self):
         raise NotImplementedError()
diff --git a/jupyter_server/services/kernels/connection/channels.py b/jupyter_server/services/kernels/connection/channels.py
index a1233477d..f206a40f7 100644
--- a/jupyter_server/services/kernels/connection/channels.py
+++ b/jupyter_server/services/kernels/connection/channels.py
@@ -79,6 +79,24 @@ class ZMQChannelsWebsocketConnection(BaseKernelWebsocketConnection):
         ),
     )
 
+    kernel_ws_protocol = Unicode(
+        None,
+        allow_none=True,
+        config=True,
+        help=_i18n(
+            "Preferred kernel message protocol over websocket to use (default: None). "
+            "If an empty string is passed, select the legacy protocol. If None, "
+            "the selected protocol will depend on what the front-end supports "
+            "(usually the most recent protocol supported by the back-end and the "
+            "front-end)."
+        ),
+    )
+
+    @property
+    def write_message(self):
+        """Alias to the websocket handler's write_message method."""
+        return self.websocket_handler.write_message
+
     # class-level registry of open sessions
     # allows checking for conflict on session-id,
     # which is used as a zmq identity and must be unique.
@@ -117,13 +135,14 @@ def _default_close_future(self):
     @classmethod
     async def close_all(cls):
         """Tornado does not provide a way to close open sockets, so add one."""
-        for socket in list(cls._open_sockets):
-            await socket.close()
+        for connection in list(cls._open_sockets):
+            connection.disconnect()
+            await _ensure_future(connection._close_future)
 
     @property
     def subprotocol(self):
         try:
-            protocol = self.selected_subprotocol
+            protocol = self.websocket_handler.selected_subprotocol
         except Exception:
             protocol = None
         return protocol
@@ -520,7 +539,7 @@ def _on_zmq_reply(self, stream, msg_list):
             self.close()
             return
         channel = getattr(stream, "channel", None)
-        if self.selected_subprotocol == "v1.kernel.websocket.jupyter.org":
+        if self.subprotocol == "v1.kernel.websocket.jupyter.org":
             bin_msg = serialize_msg_to_ws_v1(msg_list, channel)
             self.write_message(bin_msg, binary=True)
         else:
diff --git a/jupyter_server/services/kernels/websocket.py b/jupyter_server/services/kernels/websocket.py
index 70ac886ea..e7a0cfad8 100644
--- a/jupyter_server/services/kernels/websocket.py
+++ b/jupyter_server/services/kernels/websocket.py
@@ -179,7 +179,7 @@ async def pre_get(self):
         kernel = self.kernel_manager.get_kernel(self.kernel_id)
         self.connection = self.kernel_websocket_connection_class(
             parent=kernel,
-            write_message=self.write_message,
+            websocket_handler=self,
         )
 
         if self.get_argument("session_id", None):