cannot connect PS4 to Orbi56

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?
Try the PS4 wired to the Orbi router?

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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.

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 WPA2 and AES only.

Try disabling the following and see:
MIMO, Daisy Chain, Fast Roaming, IPv6 and Set 20/40Mhz Coexistence to 40Mhz only. Save settings and reboot the router and satellite(s).
Disney Circle: https://community.netgear.com/t5/Orbi/WARNING-Firmware-2-2-1-210-is-junk/m-p/1667485/highlight/true#M45926

If you updated to recent FW v.210, try enabling Daisy Chain. Some have mentioned that this seems to be working in reverse order, enabling means disabled actually.