I use QNAP NetBak Replicator 4.5.1007. A message shows: "The server and the share folder cannot be accessed. Please check the network connection and make sure the server has been turned on.", but I can connect by browser to QNAP server.
One is the browser connection and the other is a LAN share that needs to be configured in a different way. The message above says there is problem accessing the Share folder which means you have to check the share folders on the computer where they're configured and then eventually, restart the network interface by simply rebooting the PC.
I recommend downloading the manual for this application through the following link: http://eu1.qnap.com/Storage/Manual/NetBak_Replicator_Manual_ENG.pdf
In the manual you will find details and instructions on how to properly use and configure the application.