diff --git a/extensions/matrix/src/matrix/client.test.ts b/extensions/matrix/src/matrix/client.test.ts
index 3c9f625c70d..15a1fac480e 100644
--- a/extensions/matrix/src/matrix/client.test.ts
+++ b/extensions/matrix/src/matrix/client.test.ts
@@ -718,6 +718,15 @@ describe("resolveMatrixConfig", () => {
       "Matrix homeserver must use https:// unless it targets a private or loopback host",
     );
   });
+
+  it("accepts internal http hostnames when the private-network opt-in is explicit", async () => {
+    await expect(
+      resolveValidatedMatrixHomeserverUrl("http://localhost.localdomain:8008", {
+        dangerouslyAllowPrivateNetwork: true,
+        lookupFn: createLookupFn([{ address: "127.0.0.1", family: 4 }]),
+      }),
+    ).resolves.toBe("http://localhost.localdomain:8008");
+  });
 });
 
 describe("resolveMatrixAuth", () => {
diff --git a/extensions/matrix/src/matrix/client/config.ts b/extensions/matrix/src/matrix/client/config.ts
index 1b29bd30f1e..12652525b3f 100644
--- a/extensions/matrix/src/matrix/client/config.ts
+++ b/extensions/matrix/src/matrix/client/config.ts
@@ -510,10 +510,16 @@ export async function resolveValidatedMatrixHomeserverUrl(
     lookupFn?: LookupFn;
   },
 ): Promise<string> {
-  const normalized = validateMatrixHomeserverUrl(homeserver, opts);
+  const allowPrivateNetwork =
+    typeof opts?.dangerouslyAllowPrivateNetwork === "boolean"
+      ? opts.dangerouslyAllowPrivateNetwork
+      : opts?.allowPrivateNetwork;
+  const normalized = validateMatrixHomeserverUrl(homeserver, {
+    allowPrivateNetwork,
+  });
   await assertHttpUrlTargetsPrivateNetwork(normalized, {
     dangerouslyAllowPrivateNetwork: opts?.dangerouslyAllowPrivateNetwork,
-    allowPrivateNetwork: opts?.allowPrivateNetwork,
+    allowPrivateNetwork,
     lookupFn: opts?.lookupFn,
     errorMessage: MATRIX_HTTP_HOMESERVER_ERROR,
   });