First off try a Factory reset on the satellites and router then set up from scratch. This isn't a FW issue. More or less a auto update issue.
Others have said that doing a factory reset has helps resolve this. Others have also manually loaded the FW files and setup from scratch.
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?
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. This can be a factor as well.
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.
If you downgrade the autoupdate will just push it back to v210.
https://community.netgear.com/t5/Orbi/Your-experience-with-Firmware-2-2-1-210-released-as-of-10-3-18...
https://community.netgear.com/t5/Orbi/Firmware-2-2-1-210-released-as-of-10-3-18/m-p/1647303/highligh...
https://community.netgear.com/t5/Orbi/RBK40-Download-Speed-Slows-Down-After-5-Days/m-p/1643475/highl...
