WordPress updates being blocked by proxy

WP_HTTP_Proxy () adds proxy support for http API.
You can ask for the info if you don’t know already & put it into wp-config.php

define('WP_PROXY_HOST', '192.168.x.x');
define('WP_PROXY_PORT', '8080');
define('WP_PROXY_BYPASS_HOSTS', 'localhost, www.example.com, *.wordpress.org');

Source: https://developer.wordpress.org/reference/classes/wp_http_proxy/

If username & password is mandatory then, add these lines too

define('WP_PROXY_USERNAME', '_username_');
define('WP_PROXY_PASSWORD', 'xxxxxxxxx');