Note:

If your firmware version is 2.2.1.210 or lower, you cannot update the firmware directly to v2.3 or higher. You must first update the firmware to v2.2.1.212 using the manual firmware update feature in the router web interface.  After updating the firmware to v2.2.1.212, your Orbi router reboots, and then you can update to higher versions.

Security Fixes:

Download Link : 

RBR20 : https://www.downloads.netgear.com/files/GDC/RBK20/RBR20-V2.3.5.36.zip

RBS20 : https://www.downloads.netgear.com/files/GDC/RBK20/RBS20-V2.3.5.36.zip

Firmware Update Instructions:

To update your product’s firmware, follow the instructions in your product’s user manual. To find your user manual, visit https://www.netgear.com/support/, enter your model number in the search box, and click the Documentation button on the product page.