To help those who’re looking for a specific version of the Kerio VPN client. The former is more versatile, since it lets you to use any any VPN client software supporting L2TP/IPsec, but it’s widely known to be a less secure choice (for good reasons – more info ) if you want to take the most secure solution, the latter is definitely your best choice: however, being it a Kerio proprietary protocol, you’ll need to use the Kerio Control VPN Client only, which is not available for a most of platforms – including Android and iOS mobile browsers.