Ok, back in action.
PowerShell instead of CMD is fine by me. Still, I get the error
ERROR 50 (0x00000032) Accessing Destination Directory \truenas\somehtingsomething\ The request is not supported.
when using this command:
robocopy “D:something” "\10.0.40.8\destination" /E /MIR /DCOPY:D /COPY:DT /R:2 /W:5 /TEE /LOG:“C:\Users\username\Desktop\backup.txt” /XD “D:\pleasenot” /XD “D:\please not”
Same happens if I add it as a network drive and assign Z: to it.
Any ideas what the problem could be?
Update: Turning off alternate data streams and SMB2/3 locks and restarting SMB service solved the issue!