diff --git a/system/CodeIgniter.php b/system/CodeIgniter.php
index 90a9fdc619e0..da21ffffd4fe 100644
--- a/system/CodeIgniter.php
+++ b/system/CodeIgniter.php
@@ -680,7 +680,7 @@ public function displayPerformanceMetrics(string $output): string
 	 * @param RouteCollectionInterface $routes An collection interface to use in place
 	 *                                         of the config file.
 	 *
-	 * @return array
+	 * @return string
 	 */
 	protected function tryToRouteIt(RouteCollectionInterface $routes = null)
 	{
diff --git a/system/Router/Router.php b/system/Router/Router.php
index f2535d47b768..e10f3f27bad4 100644
--- a/system/Router/Router.php
+++ b/system/Router/Router.php
@@ -174,9 +174,9 @@ public function handle(string $uri = null)
 
 		if ($this->checkRoutes($uri))
 		{
-			if ($this->collection->isFiltered($uri))
+			if ($this->collection->isFiltered($this->matchedRoute[0]))
 			{
-				$this->filterInfo = $this->collection->getFilterForRoute($uri);
+				$this->filterInfo = $this->collection->getFilterForRoute($this->matchedRoute[0]);
 			}
 
 			return $this->controller;
diff --git a/tests/system/Router/RouterTest.php b/tests/system/Router/RouterTest.php
index 6a6bd201d497..61bf929b0cd3 100644
--- a/tests/system/Router/RouterTest.php
+++ b/tests/system/Router/RouterTest.php
@@ -285,6 +285,110 @@ public function testRouteWorksWithFilters()
 
 	//--------------------------------------------------------------------
 
+	/**
+	 * @see https://github.com/codeigniter4/CodeIgniter4/issues/1247
+	 */
+	public function testGroupedResourceRoutesWithFilters()
+	{
+		$group = [
+			'api',
+			[
+				'namespace' => 'App\Controllers\Api',
+				'filter'    => 'api-auth',
+			],
+			function (RouteCollection $routes) {
+				$routes->resource('posts', [
+					'controller' => 'PostController',
+				]);
+			},
+		];
+
+		// GET
+		$this->collection->setHTTPVerb('get');
+
+		$this->collection->group(...$group);
+
+		$router = new Router($this->collection);
+
+		$router->handle('api/posts');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('index', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+
+		$router->handle('api/posts/new');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('new', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+
+		$router->handle('api/posts/50');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('show', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+
+		$router->handle('api/posts/50/edit');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('edit', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+
+		// POST
+		$this->collection->setHTTPVerb('post');
+
+		$this->collection->group(...$group);
+
+		$router = new Router($this->collection);
+
+		$router->handle('api/posts');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('create', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+
+		// PUT
+		$this->collection->setHTTPVerb('put');
+
+		$this->collection->group(...$group);
+
+		$router = new Router($this->collection);
+
+		$router->handle('api/posts/50');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('update', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+
+		// PATCH
+		$this->collection->setHTTPVerb('patch');
+
+		$this->collection->group(...$group);
+
+		$router = new Router($this->collection);
+
+		$router->handle('api/posts/50');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('update', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+
+		// DELETE
+		$this->collection->setHTTPVerb('delete');
+
+		$this->collection->group(...$group);
+
+		$router = new Router($this->collection);
+
+		$router->handle('api/posts/50');
+
+		$this->assertEquals('\App\Controllers\Api\PostController', $router->controllerName());
+		$this->assertEquals('delete', $router->methodName());
+		$this->assertEquals('api-auth', $router->getFilter());
+	}
+
+	//--------------------------------------------------------------------
+
 	/**
 	 * @see https://github.com/codeigniter4/CodeIgniter4/issues/1240
 	 */