I know this is unrelated to WiFi, but there's one more thing waiting to be added to the mainline OpenWrt for BPI-R4. Currently there's no way to set MTU higher than 2030 on ethernet ports. There's a patch for the official BPI image though: A new dual 10G router based on Filogic 880 (Banana Pi BPi-R4) - #346 by pmisch