diff --git a/python/sglang/srt/utils/network.py b/python/sglang/srt/utils/network.py
index be36df9b9..cec89c715 100644
--- a/python/sglang/srt/utils/network.py
+++ b/python/sglang/srt/utils/network.py
@@ -54,8 +54,17 @@ MAX_VALID_PORT = 65535
 
 
 def wait_port_available(
-    port: int, port_name: str, timeout_s: int = 30, raise_exception: bool = True
+    port: int,
+    port_name: str,
+    timeout_s: Optional[int] = None,
+    raise_exception: bool = True,
 ) -> bool:
+    if timeout_s is None:
+        # A killed server can hold its ports well past kill_process_tree()'s
+        # return while GPU teardown completes (>30s observed on GB300), so CI
+        # raises this via SGLANG_WAIT_PORT_TIMEOUT before relaunching a server
+        # on the same port plan.
+        timeout_s = int(os.environ.get("SGLANG_WAIT_PORT_TIMEOUT", "30"))
     if port < 0 or port > MAX_VALID_PORT:
         raise ValueError(
             f"{port_name} has invalid port number {port}. "
diff --git a/python/sglang/test/test_utils.py b/python/sglang/test/test_utils.py
index 773b1c888..6140b032f 100644
--- a/python/sglang/test/test_utils.py
+++ b/python/sglang/test/test_utils.py
@@ -927,6 +927,11 @@ def popen_launch_server(
         merged.update(env)
         env = merged
 
+    # A dying predecessor can hold the derived port plan past
+    # kill_process_tree() while GPU teardown completes; give CI launches
+    # teardown-sized patience (see wait_port_available).
+    env.setdefault("SGLANG_WAIT_PORT_TIMEOUT", "120")
+
     # Store per-run marker path for potential invalidation
     per_run_marker_path = None
     try: