Why would someone want to use AP mode vs Router Mode?

[gseargeant]

i am trying to learn more about my router and satellite.  I have RBR20 router and one RBS20 satelline.  I am reading about router and AP modes but do not understand why we would need to change from router to AP.  i did see something about enhancing performance and i really want to understand more about it.  We have TVs, Xbox, PCs, and iphones connected to our internet.  Nothing is hardwire.  It is all WIFI.  i am trying to enhance the range because it seems that when we are on one end of the house w/ no satellite or router close the connection is very low.  the router is in the middle of the house in an open are and teh satellite is on one end of the house near the bedrooms.  I want to have better connection on the other end of the house and want to see if changing modes may help vs trying to find and buy and another satellite.  the system we have is for 4000 squar feet and should be more than enough but it is not performing as well as well as i expected.  would changing the modes help? will it cause issues w/ the devices.  I am not very tech savy and do not want to have to configure each device.  any help would be greatly appreciated. 

[CrimpOn]

Access Point (AP) mode is useful when the customer already has a "router" and having two routers is causing issues with specific applications.  Netgear describes the situation this way: https://kb.netgear.com/30186/What-is-Double-NAT 

If your ISP device is a "modem only", then the Orbi must be in router mode or it cannot work.

The Orbi "mode" has nothing to do with WiFi coverage.  The radios are the same in either case.

[FURRYe38]

AP mode is meant for a configuration with a router or modem that has a router built in already. 

https://community.netgear.com/t5/Cable-Modems-Routers/What-s-the-Difference-Between-a-Cable-Modem-an...
This would be a double NAT condition which isn't recommended. https://kb.netgear.com/30186/What-is-Double-NAT
https://kb.netgear.com/30187/How-to-fix-issues-with-Double-NAT

What is the Mfr and model# of the ISP modem the NG router is connected too?

30 feet is recommended in between RBR and RBS to begin with depending upon building materials when wirelessly connected. https://kb.netgear.com/000036466/How-far-should-I-place-my-Orbi-satellite-from-my-Orbi-router

[btonetbone]

I need to use AP Mode. I have a fiber connection and my ISP requires me to use their network box (essentially an all-in-one modem that can serve as a router and even broadcast WiFi). However, the network box's WiFi is not the strongest, so I purchased the Orbi system to work in conjunction with it.

I allow the network box to serve as my router (essentially the brains of my network, providing IP addresses and serving as a basic firewall). My Orbi simply broadcasts WiFi and allows devices to connect to the network.

Does that clarify?