diff --git a/vllm/distributed/device_communicators/symm_mem.py b/vllm/distributed/device_communicators/symm_mem.py
index 8c174602c3c..5621514020e 100644
--- a/vllm/distributed/device_communicators/symm_mem.py
+++ b/vllm/distributed/device_communicators/symm_mem.py
@@ -87,6 +87,25 @@ class SymmMemCommunicator:
             self.max_size = SYMM_MEM_ALL_REDUCE_MAX_SIZES[self.device_capability][
                 self.world_size
             ]
+        from vllm.distributed.parallel_state import in_the_same_node_as
+
+        if not all(in_the_same_node_as(self.group, source_rank=0)):
+            # Cross-node group (multi-node NVLink): the default CUDA backend
+            # exchanges CUDA IPC handles, which are same-node only. Select
+            # the NVSHMEM backend before the process's first symm-mem
+            # allocation so rendezvous maps fabric-reachable peer VAs.
+            try:
+                torch_symm_mem.set_backend("NVSHMEM")
+                logger.info_once(
+                    "SymmMemCommunicator: multi-node group, using the "
+                    "NVSHMEM symmetric-memory backend"
+                )
+            except RuntimeError as e:
+                logger.warning_once(
+                    "SymmMemCommunicator: could not select the NVSHMEM "
+                    "backend for a multi-node group: %s",
+                    str(e),
+                )
         try:
             self.buffer = torch_symm_mem.empty(
                 self.max_size // self.dtype.itemsize,