TCP/IP NetBIOS helper service
If the TCP/IP NetBIOS helper service is set to disabled, set it to start manual and activate/ start the service.
If you can succesfully access your NAS SMB share(s), you could set the service to start automatic.
The netbios helper service enables support for NetBIOS over TCP/IP (NetBT) service and NetBIOS name resolution.
If you want more info about the NetBIOS helper service, search the internet.
After changing the security settings, it worked in this case!