Try visiting http://www.yoursite.com/xmlrpc/index.php from your browser. You should receive an error of "XML error: no element found at line 1, column 0". If you receive any other error, you have a problem with your site setup. In this case you should first make sure that you have the xmlrpc directory's files and then check your .htaccess file for any rules which could be disabling access to that directory.
If you receive that exact error I mentioned, make sure that:
1. The Web Services is enabled in Joomla!'s Global Configuration
2. You have installed Akeeba Backup 3.1.5
3. You have installed plg_jpremote version 3.1.b2. If unsure, install it again.
4. You have published plg_jpremote (it installs as unpublished by default)
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!