We have Service Desk Professional 9.0 Build 9029 (max amount of IT assets is 1100).

We have about 500 workstations in our domain. And we have some issues with workstations scanning. About 100 errors occur when we start Windows Domain Scan. You can see the screen shot with errors: "No response received from workstation. Probably the workstation might be switched off or does not exist" and "General failure while performing the operation".

But all these workstations are turned on, we can ping them from SD+ server using simple DNS name (host name), SD+ Agents installed on all workstations. The firewall is turned off on all workstations. No results.

There's also another problem: we don't want to scan our printers, but they are being scanned/discovered. They are being put into the Workstation group, not Printer group. We never ran Network Scan, only Windows Domain Scan. 

How can we overcome those issues? I attached log from our SD+.