Orbi App Speed Test vs Actual

What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too? Is this the CM modem you listed in you product list? You using the RBR20? 

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 RBR and RBS to begin with depending upon building materials when wirelessly connected. https://kb.netgear.com/000036466/How-far-should-I-place-my-Orbi-satellite-from-my-Orbi-router

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?

Try enabling Beamforming and MIMO(MIMO may or maynot be needed) and WMM. Under Advanced Tab/Advanced Settings/Wireless Settings

Try disabling the following and see:
Armor, Circle, Daisy Chain, Fast Roaming, IPv6 and Set 20/40Mhz Coexistence to 40Mhz only. Set Short preamble instead of Long preamble modes. Save settings and reboot the router and satellite(s).

You may want to update FW if you haven't already:

https://community.netgear.com/t5/Orbi/RBR20-RBS20-2-5-1-16-firmware-observations/td-p/1897766/jump-to/first-unread-message