Appreciate input on write speeds

[ejn1111]

Hi all, trying to understand speeds a bit with my first Freenas. At moment, it's equipped with a X11-SSH with a E21230v5 Xeon running 24GB ram, FreeNas 11.3. I've set up a Raidz2 pool with 6-4TB WD Red's.... At moment network connection is 1G. I'm copying files from my Synology DS412+ to the Freenas Pool and write speeds are around 20-30Mb/s. The network stats are showing around 200MB/s. I'm sure the system is far from optimized but this still feels very slow. The Synology is rated around 200MB/s read speed. Appreciate any input.
Thanks!