diff --git a/charts/retool/values.yaml b/charts/retool/values.yaml
index 33f80bb..49a79da 100644
--- a/charts/retool/values.yaml
+++ b/charts/retool/values.yaml
@@ -1071,7 +1071,7 @@ agentSandbox:
     # Defaults to http://<fullname>:3000 (same-cluster backend service).
     backendUrl: ''
     backendDomainSuffixes: ''
-    sandboxProxyTimeoutMs: ''
+    sandboxProxyTimeoutMs: '180000'  # 3 minutes
     service:
       # Set to LoadBalancer or NodePort to expose the proxy externally.
       type: ClusterIP
diff --git a/values.yaml b/values.yaml
index 33f80bb..49a79da 100644
--- a/values.yaml
+++ b/values.yaml
@@ -1071,7 +1071,7 @@ agentSandbox:
     # Defaults to http://<fullname>:3000 (same-cluster backend service).
     backendUrl: ''
     backendDomainSuffixes: ''
-    sandboxProxyTimeoutMs: ''
+    sandboxProxyTimeoutMs: '180000'  # 3 minutes
     service:
       # Set to LoadBalancer or NodePort to expose the proxy externally.
       type: ClusterIP