If your clients cannot communicate with your Altaro Offsite Server (AOS), ensure that the Server Address being referenced from the Cloud Management Console is correct.

In order to change this simply go to [Setup] > [Altaro Offsite Servers] menu item from the left hand side and then click on [Manage] on the AOS you're having issues with.

Click on [Change Connection Details] in order to edit the Server Address for your AOS.