RBR750 running firmware 4.6.9.11 disconnects from Internet

[pbojja]

I have a RBR750 which recently updated to firmware V4.6.9.11, it is connected to two RBS750 satellites (running the same firmware version). I've observed the RBR750 router doesn't any warning light on it but disconnects from the internet modem. When i manually power cycle the RBR750, the internet is restored momentarily and it goes down right after 5-6 mins. I started seeing this problem recently after the firmware upgrade. I am not sure what changed in that firmware version to cause these RBR750 disconnection issues. 

[ekhalil]

Such intermittent issues are indications of double routing (double NAT), but of course it can be something else.
What is the make and model of the ISP modem/router to which Orbi is connected please?
Please describe your network as much as possible for us to be able to help you.

[FURRYe38]

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 

Has a power off for 1 minute then back ON with the ISP modem and router been performed since last update?
Be sure to restart your network in this sequence:
Turn off and unplug modem.
Turn off router and computers.
Plug in and turn on modem. Wait 2 minutes for it to connect.
Turn on the router and wait 2 minutes for it to connect.
Turn on computers and rest of network.

Has a factory reset and setup from scratch been performed since last FW update?