diff --git a/tests/router_unit_tests/test_router_helper_utils.py b/tests/router_unit_tests/test_router_helper_utils.py
index 848a6c28a57..d5fe819008e 100644
--- a/tests/router_unit_tests/test_router_helper_utils.py
+++ b/tests/router_unit_tests/test_router_helper_utils.py
@@ -2833,3 +2833,14 @@ def test_upsert_deployment_clears_stale_budget_config(monkeypatch):
 
     router.upsert_deployment(deployment=unbudgeted)
     assert budget_limiter._get_budget_config_for_deployment(model_id) is None
+
+
+def test_update_router_config_accepts_retry_policy():
+    """GH#31308: UpdateRouterConfig must accept retry_policy so
+    it is not silently dropped when set via UI or /config/update."""
+    from litellm.types.router import UpdateRouterConfig
+
+    config = UpdateRouterConfig(
+        retry_policy={"RateLimitErrorRetries": 3}
+    )
+    assert config.retry_policy == {"RateLimitErrorRetries": 3}