How to properly expand a WiFi network?

Question

WiFi

There are two Asus RT-N16 routers. At the moment, it is configured as follows:
On the first one, dhcp is disabled and hybrid mode is enabled and the second point is connected via wds:

On the second, dhcp is disabled and AP mode is enabled:

DHCP server on FreeBSD => from it a stupid switch for 5 ports => from it to asus1 and in asus2
Whether the question is correct implementation? Both routers are connected by wires. For WiFi, channel 6 is selected.
In general, the problem was initially in the video baby monitor, which, if turned on, greatly affects the operation of the wifi network - it works slowly, changing channels did not help, I decided to put two routers at different ends of the apartment, before that there was one in the center of the apartment and the nanny was in the process of working as once within the range of the wireless network: a camera for children in it, then a WiFi router, then a large room and then a kitchen, being with a parent unit, then in a large room, then in the kitchen it is very problematic to use gadgets via WiFi or watch something from TV on the same wifi.
PS The 9th version of the firmware is stubbornly not installed on the second router, I don’t understand why, but it’s so, all of a sudden someone came across and can tell.