diff --git a/internal/handler/app/client_asset.go b/internal/handler/app/client_asset.go
index cc898a13..179cbd67 100644
--- a/internal/handler/app/client_asset.go
+++ b/internal/handler/app/client_asset.go
@@ -801,6 +801,15 @@ func packageStatusName(status int) string {
 	}
 }
 
+// clientDeviceLANIP 网关未返回局域网网关地址（空或仅空白）时使用设备默认网关地址，保证 C 端可进入设备后台。
+func clientDeviceLANIP(lanIP *string) *string {
+	if lanIP != nil && strings.TrimSpace(*lanIP) != "" {
+		return lanIP
+	}
+	defaultIP := constants.DefaultDeviceLANIP
+	return &defaultIP
+}
+
 // mapDeviceGatewayInfoToClientInfo 将 B 端 DeviceGatewayInfo 映射为 C 端 DeviceRealtimeInfo
 // B 端和 C 端结构独立，通过映射函数转换（per D-08）
 func mapDeviceGatewayInfoToClientInfo(g *dto.DeviceGatewayInfo) *dto.DeviceRealtimeInfo {
@@ -844,7 +853,7 @@ func mapDeviceGatewayInfoToClientInfo(g *dto.DeviceGatewayInfo) *dto.DeviceRealt
 	info.WifiPassword = g.WifiPassword
 	info.IPAddress = g.IPAddress
 	info.WANIP = g.WANIP
-	info.LANIP = g.LANIP
+	info.LANIP = clientDeviceLANIP(g.LANIP)
 	info.MACAddress = g.MACAddress
 	info.DailyUsage = g.DailyUsage
 	info.DLStats = g.DLStats
diff --git a/internal/handler/app/client_asset_lan_ip_test.go b/internal/handler/app/client_asset_lan_ip_test.go
new file mode 100644
index 00000000..5baf3029
--- /dev/null
+++ b/internal/handler/app/client_asset_lan_ip_test.go
@@ -0,0 +1,39 @@
+package app
+
+import (
+	"testing"
+
+	"github.com/break/junhong_cmp_fiber/internal/model/dto"
+	"github.com/break/junhong_cmp_fiber/pkg/constants"
+)
+
+func TestMapDeviceGatewayInfoToClientInfo_LANIPDefault(t *testing.T) {
+	strPtr := func(s string) *string { return &s }
+	cases := []struct {
+		name  string
+		lanIP *string
+		want  string
+	}{
+		{name: "网关未返回", lanIP: nil, want: constants.DefaultDeviceLANIP},
+		{name: "空字符串", lanIP: strPtr(""), want: constants.DefaultDeviceLANIP},
+		{name: "仅空白", lanIP: strPtr("  "), want: constants.DefaultDeviceLANIP},
+		{name: "网关有值", lanIP: strPtr("192.168.0.1"), want: "192.168.0.1"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			info := mapDeviceGatewayInfoToClientInfo(&dto.DeviceGatewayInfo{LANIP: tc.lanIP})
+			if info.LANIP == nil || *info.LANIP != tc.want {
+				t.Fatalf("期望 %q，实际 %v", tc.want, info.LANIP)
+			}
+		})
+	}
+}
+
+// 网关调用失败时同样返回默认地址，前端仍可进入设备后台。
+func TestMapDeviceGatewayInfoToClientInfo_GatewayFailedStillDefaultLANIP(t *testing.T) {
+	msg := "网关调用失败"
+	info := mapDeviceGatewayInfoToClientInfo(&dto.DeviceGatewayInfo{GatewayMsg: &msg})
+	if info.LANIP == nil || *info.LANIP != constants.DefaultDeviceLANIP {
+		t.Fatalf("期望默认地址，实际 %v", info.LANIP)
+	}
+}
diff --git a/pkg/constants/device_network.go b/pkg/constants/device_network.go
new file mode 100644
index 00000000..914bc82f
--- /dev/null
+++ b/pkg/constants/device_network.go
@@ -0,0 +1,4 @@
+package constants
+
+// DefaultDeviceLANIP 网关未返回设备局域网网关地址时 C 端使用的默认值（设备出厂默认网关）。
+const DefaultDeviceLANIP = "192.168.1.1"