You have a backup of a machine with large disks (usually 1 TB and larger).
When you go to Web Restore Console to browse the files on the disk, you see the error:
Server is not available at the moment.
The issue might occur with large archives.
Use Cyber Protection console or Bootable Media to restore.
If you have a question or need further assistance, please make a screenshot, copy the full text of the error message and contact Acronis Support.