I'm having some problems getting full WIFI 6 downlink speeds (uplink is good) from my NAS using my R750. Note, i have another WiFi 6 AP (Asus AX92U) which i troubleshooted with. This AP did not have the same speed problems.
Hardware I used to test:
Truenas build with 2.5gbe NICs (as iperf3 server/client).
Windows 10 PC with intel AX200 (Also tested with usb 2.5gbe NIC)
Windows 10 Laptop with intel AX210 (Also tested with usb 2.5gbe NIC)
Oneplus 9 pro - WiFi 6 capable.
R750 (Unleashed - 188.8.131.52.195) connected to 2.5gbe LAN port on NAS, set up using Bridging within truenas.
2.5gbe NIC with Windows 10 PC: 2.352Gb DOWN / 1.952Gb UP
Windows 10 with AX200/AX210: 520Mb DOWN / 904Mb UP
BONUS SpeedFlex results:
OP9: TCP: 490Mb DOWN / 1.05Gb UP
Did you try using IPERF through the Ruckus and not Speedflex as is usually pretty accurate but can have issues if there are other processes using the CPU? What switching platform are you using for the 2.5gb links on the wireless and what is the poe power in wattage you are getting to the Ruckus R750? Are you using a POE injector or a POE switch?