Ithankfully, The hba is running at PCIE gen 3 x8 and the NIC is running at PCIE gen 2 x8 so that’s good and expected for your hardware choices.
Can you provide an example of how you are testing? Where are you copying to and from? From the iscsi drive to the iscsi drive? From your c drive to the iscsi drive? What type of files?
If you can, I’d be interested in seeing what local performance looks like. This will remove the iscsi variable and help us identify if there’s a problem that exists in the system itself or if the problem is with the iSCSI performance between your client and the NAS.
You can use the tool I wrote for this potentially