We have been having an ongoing issue with the built-in Windows Server Backup on our Windows Server 2016 Essentials. It has been very inconsistent since install of the server. We may get a run of 3 or 4 successful backups then a run of 3 or 4 backups that say completed with warnings. The error we are getting when it completes with warnings is Windows Server Storage VSS Writer - The writer's timeout expired between the freeze and thaw events. We have already increased the timeout and the server is currently up-to-date with updates.
The EFI System Partition, C Drive, and Recovery backup without issues. The Bare metal recovery back says backup failed to complete. The System state says backup canceled. System state backup was canceled.