LAN to LAN or WiFi to LAN or NAT LAN to LAN?
LAN to LAN doesn't make sense, as its only over the switch.
NAT LAN to LAN that seems about right, any faster than that is only via stock with the hardware NAT support (although that potentially creates its own compatibility issues).
Also, were you running iperf on the router itself, as that is not recommended as it WILL be CPU bound. eg on my Archer C7 running iperf on the router only achieves 148Mbit max but from a PC on WiFi to LAN it does up to 500Mbit.
Speed tests should always be PC to PC where there is unlikely to be a CPU bottleneck. I also would recommend iperf3 rather than iperf, as I have had iperf results when testing over the Internet that were completely impossible - faster than my broadband speed.
Zen Internet (74Mbit/16Mbit) Steam/XBOX:
Alex Atkin UK PSN/WiiU:
AlexAtkinUK Website: http://csdprojects.co.ukRouter (pfSense): Intel DN2800MT WiFi (OpenWRT):
TP-Link Archer C7 v2, TP-Link WDR3600 x2, Buffalo WZR-HP-G300NH x2.