diff --git a/src/app/Http/Controllers/API/V4/Admin/UsersController.php b/src/app/Http/Controllers/API/V4/Admin/UsersController.php
--- a/src/app/Http/Controllers/API/V4/Admin/UsersController.php
+++ b/src/app/Http/Controllers/API/V4/Admin/UsersController.php
@@ -421,4 +421,21 @@
                 'message' => self::trans('app.user-update-success'),
         ]);
     }
+
+    /**
+     * Inspect what kolab4 sees from the request.
+     *
+     * Useful for testing proxy settings and making sure the X-Forwarded-For Header is picked up.
+     *
+     * @return \Illuminate\Http\JsonResponse The response
+     */
+    public function inspectRequest(Request $request)
+    {
+        return response()->json([
+            'ip' => $request->ip(),
+            'clientIps' => $request->getClientIps(),
+            'isFromTrustedProxy' => $request->isFromTrustedProxy(),
+            'headers' => $request->headers->all()
+        ]);
+    }
 }
diff --git a/src/routes/api.php b/src/routes/api.php
--- a/src/routes/api.php
+++ b/src/routes/api.php
@@ -262,6 +262,16 @@
             Route::get('stats/chart/{chart}', [API\V4\Admin\StatsController::class, 'chart']);
         }
     );
+
+    Route::group(
+        [
+            'domain' => 'admin.' . \config('app.website_domain'),
+            'prefix' => 'v4',
+        ],
+        function () {
+            Route::get('inspect-request', [API\V4\Admin\UsersController::class, 'inspectRequest']);
+        }
+    );
 }
 
 if (\config('app.with_reseller')) {