I am encountering the same issues as his other NAS.
My NAS is running FreeNAS 11.3-U4.1
with a pool of 4 4TB Intel NVMEs in stripe
dedup and compression are set to off, sync set to off.
My issue is that the transfer will start and accomplish ~900MB/s write just fine and then will come to a halt for a few seconds before picking it back up again.
I've tried changing the record size and playing around with sync settings but no luck so far.
The SuperMicro comes with a built in 10G NIC, my network is 10G, and my iMac is also 10G so I don't think its on the network.