Help needed: Error writing image to network drive

I am trying to backup my system partitions to a network drive.

My network drive is a Synology DiskStation 213j NAS.

I am using the latest version of Macrium Reflect Standard: Version 5.4 build 7109 (Windows 8.1 64 bit).

Prior to the recent updates of Macrium Reflect I was able to make full image and incremental image backups to my network drive (Last successful backup was with build 7100).

However since the update to build 7109 I have not been able to get full or incremental images to work. The process always exits with the message

Backup aborted! - Write operation failed - An unexpected network error occurred.

To do the backup I am using the following as the name of my destination folder (I am not using a mapped drive).

\\DISKSTATION\Reflect Backups\Reflect_Backup_C
DISKSTATION is the name of the NAS "host". I have also added the NAS user name and password to Other Tasks>Edit Defaults>Network but it has not made any difference.

Note that I am able to make sizeable (> 5 GByte) file copies to the NAS so I think my network is generally working well. The DiskStation also reports it is "healthy".

Please help. I purchased Macrium Reflect to work with this NAS for backups.