LB2120 Basic Setup/Wiring

I apologize in advance for my lack of knowldege.

I recently got the LB2120 to act as a fallback "router" for a remote cabin.

The primary router is a Linksys WRT1900AC.

I have several IP cameras and a Z-Wave system at the camp that I wish to keep incontact with during Internet outages.

I have a generator and UPS at the camp to keep power alive.

I am pretty confused as to the basic wiring so that if the Internet goew out, I could continue to communicate with the camp as normal.

This is, of course, why I chose a 4G LTE Modem which "seamlessly switches the Internet from the cable modem to the celular network" upon a failure of the Internet connection..

But I"m totally confused how to wire things so that the plan works.

Although I have several devices, I can get them most of them (the wired devices) on one wire with a switch but three of the cameras are on wireless.

All of the devices have fixed IP addresses, assigned by the Linksys router, to facilitate easier access remotely to the devices.

I can also provide them on a wire from the Linksys which would continue to operate as an Intranet provider even if it lost the Internet.

The Intranet IP segment is in the 192.168.1.xxx range and, of course, the Netgear is operating on its default range of 192.168.5.xxx.

So without going on and on, could someone give me some advice on how to setup the system?

"Bridge" or "Router" mode?

What connection to make between the Linksys and the Netgear?

What other connections should I be aware of, if any?

If there is such information on the web, simply guide me to it.

I have not been able to find anything but an Internet search is only as good as the search terms and maybe I just haven't hit on the right wording. I keep getting the Netgear Manual.

Thank you for your patience and understanding. I hope this question and answer is helpful to others as well.

 S. Howard