diff --git a/vllm/v1/engine/core.py b/vllm/v1/engine/core.py
index 68c459323e0f0..3e15fbbd7589d 100644
--- a/vllm/v1/engine/core.py
+++ b/vllm/v1/engine/core.py
@@ -483,8 +483,10 @@ class EngineCoreProc(EngineCore):
         """
         input_ctx = zmq.Context()
         is_local = local_client and client_handshake_address is None
+        headless = not local_client
         handshake = self._perform_handshake(input_ctx, handshake_address,
-                                            identity, is_local, vllm_config,
+                                            identity, is_local, headless,
+                                            vllm_config,
                                             vllm_config.parallel_config)
         if client_handshake_address is None:
             with handshake as addresses:
@@ -492,7 +494,7 @@ class EngineCoreProc(EngineCore):
         else:
             assert local_client
             local_handshake = self._perform_handshake(
-                input_ctx, client_handshake_address, identity, True,
+                input_ctx, client_handshake_address, identity, True, False,
                 vllm_config)
             with handshake as addresses, local_handshake as client_addresses:
                 addresses.inputs = client_addresses.inputs
@@ -509,6 +511,7 @@ class EngineCoreProc(EngineCore):
         handshake_address: str,
         identity: bytes,
         local_client: bool,
+        headless: bool,
         vllm_config: VllmConfig,
         parallel_config_to_update: Optional[ParallelConfig] = None,
     ) -> Generator[EngineZmqAddresses, None, None]:
@@ -533,6 +536,7 @@ class EngineCoreProc(EngineCore):
                 msgspec.msgpack.encode({
                     "status": "READY",
                     "local": local_client,
+                    "headless": headless,
                     "num_gpu_blocks": num_gpu_blocks,
                     "dp_stats_address": dp_stats_address,
                 }))
diff --git a/vllm/v1/engine/utils.py b/vllm/v1/engine/utils.py
index d714daeae1545..37baa04bfbed4 100644
--- a/vllm/v1/engine/utils.py
+++ b/vllm/v1/engine/utils.py
@@ -725,13 +725,24 @@ def wait_for_engine_startup(
             raise RuntimeError(f"Message from engine with unexpected data "
                                f"parallel rank: {eng_index}")
         msg = msgspec.msgpack.decode(ready_msg_bytes)
-        status, local = msg["status"], msg["local"]
+        status, local, headless = msg["status"], msg["local"], msg["headless"]
         if local != engine.local:
             raise RuntimeError(f"{status} message from "
                                f"{'local' if local else 'remote'} "
                                f"engine {eng_index}, expected it to be "
                                f"{'local' if engine.local else 'remote'}")
 
+        # Remote engines must be headless iff we aren't in hybrid dp lb mode.
+        if not local and headless == parallel_config.data_parallel_hybrid_lb:
+            if headless:
+                raise RuntimeError(f"Remote engine {eng_index} must not use "
+                                   f"--headless in --data-parallel-hybrid-lb "
+                                   f"mode")
+            else:
+                raise RuntimeError(f"Remote engine {eng_index} must use "
+                                   f"--headless unless"
+                                   f"in --data-parallel-hybrid-lb mode")
+
         if status == "HELLO" and engine.state == CoreEngineState.NEW:
 
             # Send init message with DP config info.