If the remote server has a temporary issue, such as being temporarily offline or unavailable, then the current sync will fail but subsequent scheduled syncs will retry until all syncs have been completed.

If the remote server has a permanent issue or limitation, such as not accepting file sizes greater than 2GB or having the incorrect access permissions set, then affected files will never be successfully transferred and subsequent runs of the sync will keep repeating the transfer attempt and will keep showing failure outcomes in the logs.

To resolve these issues, make sure that the correct access permissions have been set on the remote server and that any known limitations are communicated to your users. For example, if the remote server cannot accept file sizes greater than 2GB then communicate to your users that file sizes should be kept below the 2GB limit.

To troubleshoot access permission issues, configure a connection to the remote server using credentials with full (read, write, update, delete, list, etc.) access permissions and see if the issue persists. If not, then an access permission is causing the issue. Reconfigure the access permissions one at a time and re-test the sync to determine exactly which access permission is causing the issue.