Slow WiFi speeds

[Reisender1]

I have 1-RBR 50 and 2 RBS50s. Ookla Speedtest using iPhoneX at the RBR is 234/11.8.

I have 2 iMacs (one mid-2010 the other mid-2011)  in a different room @15 feet from the RBR. Ookla Speedtest using Ookla App on iMacs is @ 35.2/13.3 for the mid-2010 and 62.2/13.0 for the mid-2011. Any suggestions on how to solve this?

[FURRYe38]

What FW is currently loaded?
What is the Mfr and model# of the ISP modem the NG router is connected too?
Is the Orbi system operating in Router or AP mode?

What is the size of your home? Sq Ft?
What is the distance between the router and satellite(s)? 30 feet is recommended in between them to begin with depending upon building materials when wirelessly connected.

What channels are you using? Auto? Try setting manual channel 1, 6 or 11 on 2.4Ghz and any unused channel on 5Ghz.
Any Wifi Neighbors near by? If so, how many?
What WPA security modes are you using?

Try enabling Beamforming and MIMO. Under Advanced Tab/Advanced Settings/Wireless Settings

Try disabling the following and see:
Daisy Chain, Fast Roaming, IPv6 and Set 20/40Mhz Coexistence to 40Mhz only. Save settings and reboot the router and satellite(s).