Error in composer update Could not resolve host: flex.symfony.com

While running php composer.phar update I've received the following error:

When I open the link in browser I'm receiving an error DNS_PROBE_FINISHED_NXDOMAIN

Tried with and without VPN, and also mobile hotspot.

My composer.json file content below.

{
    "type": "project",
    "license": "proprietary",
    "minimum-stability": "stable",
    "prefer-stable": true,
    "require": {
        "php": ">=7.4",
        "ext-ctype": "*",
        "ext-iconv": "*",
        "composer/package-versions-deprecated": "1.11.99.2",
        "doctrine/doctrine-bundle": "^2.4",
        "doctrine/doctrine-migrations-bundle": "^3.1",
        "doctrine/orm": "^2.9",
        "friendsofsymfony/jsrouting-bundle": "^2.7",
        "phpoffice/phpspreadsheet": "^1.18",
        "smsapi/php-client": "^2.6",
        "symfony/asset": "5.3.*",
        "symfony/console": "5.3.*",
        "symfony/dotenv": "5.3.*",
        "symfony/flex": "^1.3.1",
        "symfony/form": "5.3.*",
        "symfony/framework-bundle": "5.3.*",
        "symfony/mailer": "5.3.*",
        "symfony/mime": "5.3.*",
        "symfony/monolog-bundle": "^3.7",
        "symfony/proxy-manager-bridge": "5.3.*",
        "symfony/runtime": "5.3.*",
        "symfony/security-bundle": "5.3.*",
        "symfony/twig-bundle": "^5.3",
        "symfony/validator": "5.3.*",
        "symfony/yaml": "5.3.*",
        "tecnickcom/tcpdf": "^6.4",
        "twig/cssinliner-extra": "^3.3",
        "twig/extra-bundle": "^3.3",
        "twig/twig": "^2.12|^3.0"
    },
    "require-dev": {
        "symfony/debug-bundle": "^5.3",
        "symfony/maker-bundle": "^1.33",
        "symfony/stopwatch": "^5.3",
        "symfony/var-dumper": "^5.3",
        "symfony/web-profiler-bundle": "^5.3"
    },
    "config": {
        "optimize-autoloader": true,
        "preferred-install": {
            "*": "dist"
        },
        "sort-packages": true,
        "allow-plugins": {
            "symfony/flex": true,
            "symfony/runtime": true
        }
    },
    "autoload": {
        "psr-4": {
            "App\\": "src/"
        }
    },
    "autoload-dev": {
        "psr-4": {
            "App\\Tests\\": "tests/"
        }
    },
    "replace": {
        "symfony/polyfill-ctype": "*",
        "symfony/polyfill-iconv": "*",
        "symfony/polyfill-php72": "*"
    },
    "scripts": {
        "auto-scripts": {
            "cache:clear": "symfony-cmd",
            "assets:install %PUBLIC_DIR%": "symfony-cmd"
        },
        "post-install-cmd": [
            "@auto-scripts"
        ],
        "post-update-cmd": [
            "@auto-scripts"
        ]
    },
    "conflict": {
        "symfony/symfony": "*"
    },
    "extra": {
        "symfony": {
            "allow-contrib": false,
            "require": "5.3.*"
        }
    }
}

symfony / flex

Error in composer update Could not resolve host: flex.symfony.com #913