Tested 2.4GHz:
Laptop: MacBook Pro (15-inch, 2019), distance 1 meter
Router advertises 216 mpbs
Command, ran 5 times: iperf -c 192.168.0.111 -p 5201 -t 60
Stock firmware, default settings:
WiFi (laptop) <-> LAN (NAS): 76 ± 1 mbps
OpenWRT 19.07.2, default settings:
WiFi (laptop) <-> LAN (NAS): 65 ± 3 mbps
I heard that drivers are weird
UPDATE:
Switched back to stock firmware, re-tested, got results that are same as OpenWRT:
WiFi (laptop) <-> LAN (NAS): 65 ± 3 mbps
Performance testing is weird ¯_(ツ)_/¯