AX4200 wifi speeds not as good as expected

[ort84]

Recently picked up an AX4200 to replace my RBR40 Orbi mesh system. I used to get between 400-450Mbps on the RBR40. Based on the reviews I've seen online of the Wifi 6 Orbi's, I was expecting 700-800Mbps off my iPhone 11 Pro Max. I have gigabit fiber with ATT and Orbi verified 940/940 speeds to the router from the modem. 

Best I am getting is 560-580Mbps even from 5 feet away from the Orbi router. What can I do to improve the Wifi speeds?

Thanks!

[FURRYe38]

So you are getting near 900Mpbs on wired speed thru the RBR?

What is the Mfr and model# of the Internet Service Providers modem/ONT 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 or more 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?

What is the connection rate between the RBR and iPhone? Install WiFISweetSpots app on the phone. Be sure the phone is connected to the RBR first before running this app.
https://kb.netgear.com/19668/Link-Rate-and-Transfer-Speed

Try disabling the following and see:
Armor, 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).

Try changing CTS values to 2347 under Advanced Tab/Advanced Settings/Wireless Settings.