After update, rbk50 won't allow dlink 942l to go online

Factory reset and setup from scratch using same SSID and PW from before? Ive had no issues with my 3 DCS cameras working with Orbi after a FW update, factory reset and setup from scratch using same SSID name and PW. 

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 when wirelessly connected.

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 enabling Beamforming and MIMO(MIMO may or maynot be needed) and WMM. Under Advanced Tab/Advanced Settings/Wireless Settings