The possible causes explained above are valid and useful in common troubleshootings. Also duplicated/obsolete DNS records or firewall misconfigurations at the workstation level could lead to DCOM event ID 10009.
In my case, this type of error started to appear every 30 minutes (01:00, 01:30 and so on, the whole day) and most of the workstations that the server failed to connect to were powered off.
After digging a lot and by chance, I just find a simple solution: Stop (and set to manual startup) the Windows SBS Manager service.
Server is SBS 2011 with Exchange/DC/DNS/DHCP but I really don’t use the SBS Console, so finally no more polling errors.