RB971 and 4 sats, installed on router a cooling fan ... router freeze

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. 

How are the RBS connected to the RBR? Wireless or Ethernet?

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 wired or wirelessly connected. 
https://kb.netgear.com/31029/Where-should-I-place-my-Orbi-satellite ‌‌🛰

Does this happen with the RBS turned OFF? 
Does this happen with both wireless and wired devices? 
What channel configurations are currently set on the router?  

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

Try disabling the following and see:
All Logging on the RBR, Armor, IPv6, Smart Parental Controls or Circle, Traffic Meter.