With multiple clients, we were able to fully utilize the Link Aggregation Control Protocol (LACP), and the total transfer rate (throughput from all clients combined) reached 137.64 MB/s during the five-clients test. The highest read speed, 203.14 MB/s, was measured with five clients during the "ISO copy from NAS" test, while the highest write speed was measured with the same number of clients during the "Program copy to NAS" test—it was 137.77 MB/s.
The CPU easily copes with even five clients transferring huge volumes of data, and the same applies to the RAM of the NAS. Disk utilization is pretty high, which is normal since mechanic HDDs aren't that fast and transfer rates are higher with five clients.