I got a DS1515+ with LAG port (2x 1Gb), and aTV 4K, both connected via Ethernet to a Cisco switch (SG300-10P).
Using also NFS, and i got for a 4GB file an average of 313.75Mbps (using Infuse test).
PS - As NC_Bullseye said. the best test to know exatly the maximum throughput you can get in your network, is doing iPerf tests, you can install AppleTV “iPerf - Speed Test Tool” (link : iPerf - Speed Test Tool on the App Store (apple.com) and do iperf tests between aTV and other LAN devices.
Infuse tests max bandwidth used to stream the file. You probably won’t ever see anything above 350Mbps or 400. Install docker on your diskstation and then install the iperf3 package. From there you can install it on your client devices as well to test actual network throughput between devices.
I think he’s going from a pure performance perspective and not necessarily having issues. I get 275 on NFS with my system, so he’s looking to close the gap. For reference, that is with a cat 5E backbone through a gigabit switch and with AirPort Extreme routers
I don’t think with NFS. every protocol is different. Try FTP if you want speeds like that. Not sure if there are trade offs though. I feel like I read someone had issues with seeking but can’t remember. Maybe test it out and report back if you are interested in trying it out.