RAX120 Nighthawk suddenly blocked all Apple Services

What Firmware version is currently loaded?
What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too?
Be sure your using a good quality LAN cable between the modem and router. CAT6A STP is recommended. 

Be sure to disable any MAC Address randomizers on phones and pads while at home:
https://community.netgear.com/t5/Orbi-App/NETGEAR-Mobile-Applications-and-Apple-Devices-FAQ/td-p/2220016/jump-to/first-unread-message
https://community.netgear.com/t5/Nighthawk-App/NETGEAR-Mobile-Applications-and-Apple-Devices-FAQ/td-p/2220015/jump-to/first-unread-message

Any other wifi devices experiencing problems? 

What iOS version is on the Apple devices? 

Try disabling the following and see:
Armor, Smart Parental Controls or Circle, Traffic Meter.

What channels are you using? Auto? Try setting manual channel 1, 6 or 11 on 2.4Ghz and 40 to 48 channel on 5Ghz.
https://kb.netgear.com/23783/How-do-I-change-the-wireless-channel-on-my-NETGEAR-router

Has a power off for 1 minute then back ON with the ISP modem and router been performed?
Be sure to restart your network in this sequence:
Turn off and unplug modem.
Turn off router and computers.
Plug in and turn on modem. Wait 2 minutes for it to connect.
Turn on the router and wait 2 minutes for it to connect.
Turn on computers and rest of network.