diff --git a/apps/server/src/startupAccess.test.ts b/apps/server/src/startupAccess.test.ts
index fd56b4a4c86f..a48bb5263f8e 100644
--- a/apps/server/src/startupAccess.test.ts
+++ b/apps/server/src/startupAccess.test.ts
@@ -1,9 +1,11 @@
 import type * as NodeOS from "node:os";
 
 import { describe, expect, it } from "@effect/vitest";
+import * as NetAddress from "effect/net/NetAddress";
 
 import {
   acceptsPrivateNetworkConnection,
+  loopbackUrlHostForAddress,
   resolveHeadlessConnectionString,
 } from "./startupAccess.ts";
 
@@ -55,6 +57,18 @@ it("prefers a LAN address over a tailnet one for a private-network pairing URL",
   ).toBe("http://192.168.1.42:3773");
 });
 
+it("targets the bound interface when the listener binds a specific address", () => {
+  const hostFor = (ip: string) =>
+    loopbackUrlHostForAddress(NetAddress.inetAddressFromIpStringUnsafe(ip, 3773));
+
+  expect(hostFor("0.0.0.0")).toBe("127.0.0.1");
+  expect(hostFor("::")).toBe("127.0.0.1");
+  expect(hostFor("::1")).toBe("[::1]");
+  expect(hostFor("127.0.0.1")).toBe("127.0.0.1");
+  expect(hostFor("127.0.0.2")).toBe("127.0.0.2");
+  expect(hostFor("100.101.102.103")).toBe("100.101.102.103");
+});
+
 describe("acceptsPrivateNetworkConnection", () => {
   const accepts = (localAddress: string | undefined, remoteAddress: string | undefined) =>
     acceptsPrivateNetworkConnection({ localAddress, remoteAddress });
diff --git a/apps/server/src/startupAccess.ts b/apps/server/src/startupAccess.ts
index bcbfedff6089..f393faecebf9 100644
--- a/apps/server/src/startupAccess.ts
+++ b/apps/server/src/startupAccess.ts
@@ -71,9 +71,9 @@ export const acceptsPrivateNetworkConnection = (socket: {
   );
 
 export const loopbackUrlHostForAddress = (address: NetAddress.InetAddress): string =>
-  address._tag === "InetAddressV6" && NetAddress.isLoopback(address.address)
-    ? "[::1]"
-    : "127.0.0.1";
+  NetAddress.isUnspecified(address.address)
+    ? "127.0.0.1"
+    : NetAddress.formatUrlHostString(NetAddress.formatIp(address.address));
 
 const normalizeHost = (host: string): string =>
   host.startsWith("[") && host.endsWith("]") ? host.slice(1, -1) : host;