Most windows users encounter an issue where when they try and do a backup to a network drive they are prompted with the error “The validation information class requested was invalid. 0x80070544”. The most common cause of this error is the network credentials which it cannot authenticate even though, you’re entering the correct username and password with the right set of permissions.
The issue arises from the formatting Windows has specified in order to allow access which requires the user to prefix the username with that of the remote server or device for example: \\server name\username instead of just the username.
If the above did not work for you then you can try and run Powershell and execute the following command to initiate the back up.
wbadmin start backup -backuptarget:\\remoteserver\foldername -user:remoteserver\username -password:yourpassword -include:C: -allCritical -quiet
NOTE: If the Backup Drive is connected via USB to the Router then the servername is the router name, and how Windows sees it. For example: on tplink routers, the server name is tplinklogin.net
Linux or SMB Server or a NAS Device
Since all devices vary, another work around to get this sorted out on a NAS or SMB Server is to add the following parameter to the SMB.conf file.
strict allocate = yes
You will have to Google how to edit the smb.conf file. Generally the path to smb.conf on a Linux Machine is etc/samba/smb.conf and you will need to have root access to edit it.