Before I found out in practice that Linkstation Live can not handle multiple print jobs, I gathered about 15 failed print jobs in the print queue. You can not see them in Mac but only in any connected Windows computer. However, you can not clear them from Windows, nor from web admin. Even firmware update on Linkstation does not clear the failed jobs.
After using print server with one job at a time and waiting until previous job is printed, I do not get so many fails any more. However, this is at least annoying.
Anyone has any idea how to clear these?