"Unauthenticated" error on a route that is not protected - laravel

Question

Part of my application does not utilize standard user authentication, and lies outside the auth group in my routes file. I am using Laravel Passport, VueJS2, VueRouter. Laravel is serving two blade files; one for the authenticated part of the application, and the other for the non-authenticated part.
However, I find that when trying to access that part of the application, it still requires me to be authenticated (I get the 401: Unauthorized error).
I have looked through my configuration files, and I can't seem to figure out why this would be displayed.
My api.php file:
<?php
use Illuminate\Http\Request;
Route::group(['middleware' => 'auth'], function () {
// A lot of routes here...
});
// These should not be guarded
// This is the route that triggers the unauthenticated message
Route::post('authenticate', 'TestController#authenticate');
THe JS file that makes the request:
authenticateUser: function() {
var data = {
'id' : this.$route.params.id,
'passcode' : this.state.password,
};
var that = this;
axios({
method: 'post',
url: '/api/authenticate',
withCredentials: true,
data: data,
}).then(function(response) {
swal('Great!', 'You have been authenticated.', 'success');
that.$router.push('/client/create/' + that.$route.params.id);
}, function(error) {
swal('Woah!', 'Wrong password, go away.', 'error');
});
}
Here is my kernel.php file:
<?php
namespace App\Http;
use Illuminate\Foundation\Http\Kernel as HttpKernel;
class Kernel extends HttpKernel
{
/**
* The application's global HTTP middleware stack.
*
* These middleware are run during every request to your application.
*
* #var array
*/
protected $middleware = [
\Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode::class,
\Illuminate\Foundation\Http\Middleware\ValidatePostSize::class,
\App\Http\Middleware\TrimStrings::class,
\Illuminate\Foundation\Http\Middleware\ConvertEmptyStringsToNull::class,
];
/**
* The application's route middleware groups.
*
* #var array
*/
protected $middlewareGroups = [
'web' => [
\App\Http\Middleware\EncryptCookies::class,
\Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
\Illuminate\Session\Middleware\StartSession::class,
// \Illuminate\Session\Middleware\AuthenticateSession::class,
\Illuminate\View\Middleware\ShareErrorsFromSession::class,
\App\Http\Middleware\VerifyCsrfToken::class,
\Illuminate\Routing\Middleware\SubstituteBindings::class,
\Laravel\Passport\Http\Middleware\CreateFreshApiToken::class,
],
'api' => [
'throttle:60,1',
'bindings',
],
];
/**
* The application's route middleware.
*
* These middleware may be assigned to groups or used individually.
*
* #var array
*/
protected $routeMiddleware = [
'test.auth' => \App\Http\Middleware\VerifyTestAccess::class,
'auth' => \Illuminate\Auth\Middleware\Authenticate::class,
'auth.basic' => \Illuminate\Auth\Middleware\AuthenticateWithBasicAuth::class,
'bindings' => \Illuminate\Routing\Middleware\SubstituteBindings::class,
'can' => \Illuminate\Auth\Middleware\Authorize::class,
'guest' => \App\Http\Middleware\RedirectIfAuthenticated::class,
'throttle' => \Illuminate\Routing\Middleware\ThrottleRequests::class,
'test.state' => \App\Http\Middleware\VerifyTestState::class,
];
}