diff --git a/src/commands/configure.gateway.ts b/src/commands/configure.gateway.ts
index 162e1a0cf7d..84db572eb26 100644
--- a/src/commands/configure.gateway.ts
+++ b/src/commands/configure.gateway.ts
@@ -2,6 +2,7 @@ import type { OpenClawConfig } from "../config/config.js";
 import type { RuntimeEnv } from "../runtime.js";
 import { resolveGatewayPort } from "../config/config.js";
 import { findTailscaleBinary } from "../infra/tailscale.js";
+import { validateIPv4AddressInput } from "../shared/net/ipv4.js";
 import { note } from "../terminal/note.js";
 import { buildGatewayAuthConfig } from "./configure.gateway-auth.js";
 import { confirm, select, text } from "./configure.shared.js";
@@ -72,25 +73,7 @@ export async function promptGatewayConfig(
       await text({
         message: "Custom IP address",
         placeholder: "192.168.1.100",
-        validate: (value) => {
-          if (!value) {
-            return "IP address is required for custom bind mode";
-          }
-          const trimmed = value.trim();
-          const parts = trimmed.split(".");
-          if (parts.length !== 4) {
-            return "Invalid IPv4 address (e.g., 192.168.1.100)";
-          }
-          if (
-            parts.every((part) => {
-              const n = parseInt(part, 10);
-              return !Number.isNaN(n) && n >= 0 && n <= 255 && part === String(n);
-            })
-          ) {
-            return undefined;
-          }
-          return "Invalid IPv4 address (each octet must be 0-255)";
-        },
+        validate: validateIPv4AddressInput,
       }),
       runtime,
     );
diff --git a/src/shared/net/ipv4.ts b/src/shared/net/ipv4.ts
new file mode 100644
index 00000000000..3c511823c77
--- /dev/null
+++ b/src/shared/net/ipv4.ts
@@ -0,0 +1,19 @@
+export function validateIPv4AddressInput(value: string | undefined): string | undefined {
+  if (!value) {
+    return "IP address is required for custom bind mode";
+  }
+  const trimmed = value.trim();
+  const parts = trimmed.split(".");
+  if (parts.length !== 4) {
+    return "Invalid IPv4 address (e.g., 192.168.1.100)";
+  }
+  if (
+    parts.every((part) => {
+      const n = parseInt(part, 10);
+      return !Number.isNaN(n) && n >= 0 && n <= 255 && part === String(n);
+    })
+  ) {
+    return undefined;
+  }
+  return "Invalid IPv4 address (each octet must be 0-255)";
+}
diff --git a/src/wizard/onboarding.gateway-config.ts b/src/wizard/onboarding.gateway-config.ts
index e7ecac2b6d2..dae687d12cf 100644
--- a/src/wizard/onboarding.gateway-config.ts
+++ b/src/wizard/onboarding.gateway-config.ts
@@ -13,6 +13,7 @@ import {
   validateGatewayPasswordInput,
 } from "../commands/onboard-helpers.js";
 import { findTailscaleBinary } from "../infra/tailscale.js";
+import { validateIPv4AddressInput } from "../shared/net/ipv4.js";
 
 // These commands are "high risk" (privacy writes/recording) and should be
 // explicitly armed by the user when they want to use them.
@@ -85,25 +86,7 @@ export async function configureGatewayForOnboarding(
         message: "Custom IP address",
         placeholder: "192.168.1.100",
         initialValue: customBindHost ?? "",
-        validate: (value) => {
-          if (!value) {
-            return "IP address is required for custom bind mode";
-          }
-          const trimmed = value.trim();
-          const parts = trimmed.split(".");
-          if (parts.length !== 4) {
-            return "Invalid IPv4 address (e.g., 192.168.1.100)";
-          }
-          if (
-            parts.every((part) => {
-              const n = parseInt(part, 10);
-              return !Number.isNaN(n) && n >= 0 && n <= 255 && part === String(n);
-            })
-          ) {
-            return undefined;
-          }
-          return "Invalid IPv4 address (each octet must be 0-255)";
-        },
+        validate: validateIPv4AddressInput,
       });
       customBindHost = typeof input === "string" ? input.trim() : undefined;
     }