By default we block access to xmlrpc.php for security reasons. You can use Wordpress REST API as a a recommended alternative.

If you still need to use XMLRPC then click on "Profile" in sidebar and then "Profile" tab. Once there you can see "XML-RPC Whitelist". You can enter the IP address of the machine that will access xmlrpc.php. It can take up to 10 minutes for your whitelist to get updated. Once it's updated, you can access xmlrpc.php normally.