Hello,
Try performing the below step:
1. On both SC Plugin-Host Windows cluster nodes as well as SC server, Locate the ‘app settings‘ line in the "C:\Program Files\NetApp\SnapCenter\SMCore\SMCoreServiceHost.exe.Config" file.
2. add the line below underneath:
<add key="EnableWs2016NoRemoteCall" value="false" />”
3. on the plugin host(s),add the same line on the "C:\Program Files\NetApp\SnapCenter\SnapCenter Plug-in for Microsoft Windows\SnapDriveService.exe.config" file, restart the Plug-In for Windows Service and and SMCORE service and retry backup.
Let me know if this workout for you.
Thanks