Hey, I saw that you originally commented on my post (
https://www.truenas.com/community/t...ween-windows-and-smb-share.91092/#post-631137 ) before the mods condensed into one new post... I don't think your issue is related, but figured I'd explain my situation just in case... But my issue was over a year and a half ago, and I do not remember everything
Just to share my experience, it seemed that the drive setup I was using (either the drives or the configuration) was causing my write speeds to fluctuate sporadically between 80 and 20 MBps.
1) In my case, I had 3 Toshiba NAS Drives in a RAIDZ Configuration... The Drives were showing bogus SMART Errors, and I returned them under warranty, and got Seagate Exos instead... in the new configuration I had 4 Drives set up in a mirror configuration... I think the Toshiba Drives, even tho they were NAS drives, just weren't handling the heavy I/O, so I got Enterprise level drives... and I decided to change the Type of configuration, because its easier to scale up pairs of drives than scaling up a ZFS1/2/3 in my opinion.
2) I think there was an issue with network speed negotiating... IE, my router's 2.5G port was having issues negotiating with my server's 1G port... I ended up moving to a 1G port... TLDR, ensure that your 10G Port is capable of 1G negotiation.
So in my situation, between replacing the drives, changing the configuration of the vdev, and having my network interfaces in a place they could properly negotiate... my issue disappeared. and I get about 120MBps over the 1G Router port, which is basically capping out the 1GB capability of the router port.
As I said though, unfortunately, I doubt this will help you... the symptoms seem to be very different...