Laravel redirect to causes "All inertia requests must receive a valid Inertia response" when accessing over internet

Using Laravel 11 with InertiaJS and Svelte.

I have an admin.php file which has some routes guarded by the auth middleware. I want the "/admin" route to redirect to /admin/posts, or /login if the user is not logged in. Using Inertia's <Link> component, navigating to this route should redirect to /admin/posts or /login and not refresh the app.

Instead it returns All Inertia requests must receive a valid Inertia response, however a plain JSON response was received. Searching a bit, I found Inertia needs the X-Inertia header, but it's present in the response headers.

The website is behind Nginx Proxy Manager. It's set to pass headers X-Inertia and X-Inertia-Version.

Website is live for now on https://pwa.skmedia.cc. Navigating to "Administracija" should return the error. Code is on github here

The website works locally when served with php artisan serve, but when deployed on a server behind Nginx Proxy Manager, redirected Inertia Links return the error. Redirecting back with redirect()->back() works fine, but I want to redirect to some other page.

I can use Inertia::location(), but this refreshes the page which I would like to avoid.

e.g. in web.php if i have:

Route::get('/redirected', function(){ return redirect()->to('/destination'); });Route::get('/destination', function(){ return Inertia::render('Example'); });

In resources/js/Pages an empty Example.svelte file, and in my navigation something like:

<script>    import { Link } from "@inertiajs/svelte";</script><Link href="/redirected">Redirected</Link>

Clicking on that link on the website in "production" returns:

All Inertia requests must receive a valid Inertia response, however a plain JSON response was received.

while locally it redirects correctly to /destination .