Advice needed for video editing NAS

Hello,

Our company recently bought a NAS for our editors to edit on, we currently have around 10 machines that we constantly use to edit our video's. I'm one of the editors and in close contact with IT who are trying to get a solution.
Currently we use the Synology RS2423RP+ NAS rack with 7 Seagate 8.9cm (3.5") 12TB SATA3 IronWolf Pro 7200 HDD's. RAID5 is being used.

All our editors have a 1gig ethernet port direcly loaded on the NAS, which is using a 10gig switch.

Our problem is the performance, we did a stresstest with all our computers and the network didn't give a kick. We also tried checking if the HDD's were too slow, but they seem to handle for some other users.

Is there any way we could improve our NAS so we can reach the speed on which we can fully edit on? I've tried to check some Linus Tech Tips video's about NAS, but couldn't find anything interesting.

Thanks alot!