hi, it seems that veeam cannot mount smb2-only fileservers. on command line this easily accomplished using additional parameter -o vers=2.0 to the mount command.
there's a workaround, by using local folder as destination and then using pre-backup script to mount the smb2 share.
it would be nice if there's small tickbox to specify smb protocol version in the veeam console ui
btw, the bare metal recovery media also has the the same problem. you need to mount via command line first, then restore.