diff --git a/agentplatform/_genai/sandboxes.py b/agentplatform/_genai/sandboxes.py
index 649cf3a743..e551564fa1 100644
--- a/agentplatform/_genai/sandboxes.py
+++ b/agentplatform/_genai/sandboxes.py
@@ -1405,7 +1405,14 @@ def send_command(
         if psc_endpoint:
             # VPC-SC path: caller has provisioned a PSC endpoint against
             # connection_info.service_attachment and passes its host here.
-            endpoint = "https://" + psc_endpoint
+            # The forwarding rule targets the router's Service Attachment
+            # directly, and the router pod serves plain HTTP on `port` (the
+            # router NetworkPolicy allows ingress only on that TCP port).
+            # Unlike the non-VPC-SC load_balancer_hostname case, no
+            # Google-managed L7 LB terminates TLS or translates ports in
+            # front, so the URL must be http://host:port, not https://host
+            # on the default 443.
+            endpoint = f"http://{psc_endpoint}:{port}"
         elif connection_info.load_balancer_hostname:
             endpoint = "https://" + connection_info.load_balancer_hostname
         elif connection_info.load_balancer_ip:
@@ -1489,7 +1496,11 @@ def generate_browser_ws_headers(
 
         connection_info = sandbox_environment.connection_info
         if psc_endpoint:
-            ws_base_url = "wss://" + psc_endpoint
+            # See send_command's psc_endpoint branch for the rationale: the
+            # PSC forwarding rule targets the router's Service Attachment
+            # directly (no L7 LB in front), so this must be plain ws:// with
+            # the explicit port, not wss:// on the default 443.
+            ws_base_url = f"ws://{psc_endpoint}:{port}"
         elif connection_info.load_balancer_hostname:
             ws_base_url = "wss://" + connection_info.load_balancer_hostname
         elif connection_info.load_balancer_ip:
diff --git a/tests/unit/agentplatform/genai/test_sandbox.py b/tests/unit/agentplatform/genai/test_sandbox.py
index 0e6c933a16..45bf90e069 100644
--- a/tests/unit/agentplatform/genai/test_sandbox.py
+++ b/tests/unit/agentplatform/genai/test_sandbox.py
@@ -186,7 +186,11 @@ def test_send_command_vpcsc_uses_psc_endpoint(self, mock_request):
 
         args, kwargs = mock_request.call_args
         assert args[0] == "GET"
-        assert args[1] == "https://10.0.0.10/test/path"
+        # PSC-E ingress goes to the router pod directly (no Google-managed L7
+        # LB in front), and the router serves plain HTTP on the sandbox port.
+        # The URL must therefore be http://host:port, not https://host on the
+        # default 443.
+        assert args[1] == "http://10.0.0.10:9000/test/path"
         assert kwargs["headers"]["Authorization"] == "Bearer test_token"
         assert kwargs["headers"]["X-Sandbox-Routing-Token"] == "test_routing_token"
         # X-Sandbox-Port must flow through even on the VPC-SC path; the
@@ -215,7 +219,11 @@ def test_send_command_vpcsc_accepts_hostname_as_psc_endpoint(self, mock_request)
         )
 
         args, _ = mock_request.call_args
-        assert args[1] == "https://psc-endpoint.internal.example.com/test/path"
+        # Default port "8080" is baked into the URL; scheme is plain http.
+        assert (
+            args[1]
+            == "http://psc-endpoint.internal.example.com:8080/test/path"
+        )
 
     def test_send_command_raises_when_no_endpoint_available(self):
         mock_sandbox = mock.Mock()
@@ -253,7 +261,9 @@ def test_generate_browser_ws_headers_vpcsc_uses_psc_endpoint(
             timeout=3600,
             psc_endpoint="10.0.0.10",
         )
-        assert ws_url == "wss://10.0.0.10/test/endpoint"
+        # Plain ws:// with the explicit port for the same reason send_command
+        # uses http://host:port on this branch — see that method's docstring.
+        assert ws_url == "ws://10.0.0.10:8080/test/endpoint"
         assert (
             headers["Sec-WebSocket-Protocol"]
             == "v1.stream, test_token, test_routing_token, 9222"
@@ -261,7 +271,7 @@ def test_generate_browser_ws_headers_vpcsc_uses_psc_endpoint(
         # The delegated send_command call that fetches the CDP endpoint must
         # also target the PSC endpoint host, not the (empty) load balancer.
         req_args, req_kwargs = mock_request.call_args
-        assert req_args[1] == "https://10.0.0.10/cdp_ws_endpoint"
+        assert req_args[1] == "http://10.0.0.10:8080/cdp_ws_endpoint"
         assert req_kwargs["headers"]["X-Sandbox-Routing-Token"] == "test_routing_token"
 
     @mock.patch.object(sandboxes.Sandboxes, "_create")