diff --git a/web/portal/app/ModuleGrid.test.tsx b/web/portal/app/ModuleGrid.test.tsx
index e92ab96d..9910978a 100644
--- a/web/portal/app/ModuleGrid.test.tsx
+++ b/web/portal/app/ModuleGrid.test.tsx
@@ -1,5 +1,5 @@
 import { describe, expect, it, vi } from "vitest";
-import { fetchVisibleModules } from "./ModuleGrid";
+import { fetchVisibleModules, resolveModuleHref } from "./ModuleGrid";
 
 describe("fetchVisibleModules", () => {
   it("ruft die Portal-eigene Route mit tenant/role auf und gibt die Modulliste zurueck", async () => {
@@ -22,3 +22,17 @@ describe("fetchVisibleModules", () => {
     expect(modules).toEqual([]);
   });
 });
+
+describe("resolveModuleHref", () => {
+  it("ersetzt localhost durch den echten Hostnamen", () => {
+    expect(resolveModuleHref("http://localhost:3107/", "192.168.1.204")).toBe("http://192.168.1.204:3107/");
+  });
+
+  it("laesst Nicht-localhost-Hrefs unveraendert", () => {
+    expect(resolveModuleHref("http://dms.example.com:3107/", "192.168.1.204")).toBe("http://dms.example.com:3107/");
+  });
+
+  it("laesst localhost unveraendert wenn das Portal selbst auf localhost laeuft", () => {
+    expect(resolveModuleHref("http://localhost:3107/", "localhost")).toBe("http://localhost:3107/");
+  });
+});
diff --git a/web/portal/app/ModuleGrid.tsx b/web/portal/app/ModuleGrid.tsx
index 1a0b3162..c28b7556 100644
--- a/web/portal/app/ModuleGrid.tsx
+++ b/web/portal/app/ModuleGrid.tsx
@@ -23,6 +23,21 @@ export async function fetchVisibleModules(
   return body.modules ?? [];
 }
 
+export function resolveModuleHref(
+  href: string,
+  currentHostname: string = typeof window !== "undefined" ? window.location.hostname : "localhost"
+): string {
+  try {
+    const url = new URL(href);
+    if (url.hostname === "localhost" && currentHostname !== "localhost") {
+      url.hostname = currentHostname;
+    }
+    return url.toString();
+  } catch {
+    return href;
+  }
+}
+
 type State =
   | { status: "loading" }
   | { status: "error"; message: string }
@@ -76,7 +91,7 @@ export function ModuleGrid() {
       {state.modules.map((mod) => (
         <li key={mod.key}>
           <a
-            href={mod.href}
+            href={resolveModuleHref(mod.href)}
             style={{
               display: "block",
               minHeight: 44,