Intermittent and slowing drive write and read speeds

Really stumped on this one. using a DS1522+ 3 TB WD Gold Enterprise 128 MB cache drives. Shr1 raid. all drives are checking out healthy and functioning with out error.
I’m getting writes of 700mbps + and reads of 900mbps + on Black Magic Disk Speed Tests under the 1 gb test. and slightly less when running the 5 gb test. And as long as I’m accessing them through programs I get very good response speeds opening FCPX, On 1 Photo Raw. and other programs throughout the day. BUT!! anytime I let the Mac sit idle for a few hours and come back the drive speeds write and read are atrocious 30 to 40 mbps . I disconnect from the shared drive and and immediately reconnect to it and my speeds are right back up on the BlackMagic Speed Test and accessing the data on the shared folders through the various programs. until I let the Mac sit idle again for a few hours. Im new to Nas coming from a Das Is there anything I might not have setup properly? Or dose it sound like something on the Mac Studio end?

Maybe HDD hibernation? Try disabling that on the synology, see if your speeds improve.

Yes I did shut the HDD Hibernation to none from the default 20 min. But that did not seem to work.