Unable to take backup from one client

Greetings of the day.
One of our friend has suggested and implemented URbackup client and server and we have some issues. Am not well versed with this system or backup device or linux OS.
We have configured two clients for one backup server and facing the following problems.

  1. Backup from One client (Windows 7) is being taken at the specified time and frequency.
  2. Backup from another client (Windows Server 2008R2) is not at all showing in the server for setup. We have installed the latest client on the Windows server 2008R2, yet, the server is not able to configure or show the client.
  3. After every month or so, the Backup server device becomes inaccessible.
  4. At times you can access the server thru ping but when you try access thru webbrowser or try to login, we get an error server timed out.
  5. Now after two months during lockdown, when we tried to access, the backup server says “No Bootable Device Detected, Please check and reboot”. This happens quite often.
    Please can anyone help us on this regard. Am a novice and amateur and have no knowledge about linux and hope that someone could guide me or support me. Based on your inputs, can try make the changes here.