'No internet connection' attempted fix fail

Does the top ring LED turn PINK or BLINK WHITE when this happens? 

I've kept my 50 series at latest FW version and have not seen any issues. Possible loss of internet maybe at the ISP level. 

RBR and RBS need to be at same FW level as well.

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. CAT6 is recommended. 

If you havn't tried a factory reset yet, maybe time. A complete pull of the power adapters for a period of time after the factory reset then walk thru the setup wizard and setup from scratch with a wired PC and web browser.

https://kb.netgear.com/31486/How-do-I-reset-my-Orbi-system-to-factory-default-settings

https://kb.netgear.com/22697/How-do-I-install-my-NETGEAR-router-using-the-router-web-interface

How many RBS are deployed? 
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🛰

What channel configurations are currently set on the router? 

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

Be sure to disable any MAC Address randomizers on phones and pads while at home:
NETGEAR Mobile Applications and Android/Apple/Windows Devices FAQ | NETGEAR Communities