CrystalDiskMark
Gigabit Ethernet remains the dominant standard, featuring in four of the five tested NAS solutions, yet it continues to serve as a bottleneck to pure sequential throughput. Qnap's TS-451D2 has no problem saturating the interface, and good levels of performance are maintained in the demanding 4K read and write tests.
Solid numbers, and there's always the possibility of going higher if your network gear supports link aggregation, however if you need the speed it is worth considering the dearer and fundamentally faster 2.5GbE Qnap TS-453D.